THERURAL 


Agrrc. 


l&ural  Science 

EDITED  BY  L.  H.  BAIT-EY 


IRRIGATION   AND    DRAINAGE 


IRRIGATION  AND  DRAINAGE 


PRINCIPLES  AND   PRACTICE 

OF   THEIR 
CULTURAL    PHASES 


BY 


F.    H.    KING 


Professor  of  Agricultural  Physics  in  the  University  of  Wisconsin: 
Author  of  "The  Soil" 


EIGHTH  EDITION 


THE    MACMILLAN    COMPANY 

LONDON  •    MACMILLAN    &    CO.,  LTD. 

1913 

All  rights  reservzd 


A 


o 


JK ' 


COPYRIGHT  1898 
By   F,    H.    KING 


Set  up  and  electrotyped  October,  1899 

Reprinted  with  corrections  January,  1902 

Julv  1903.  January,  1906,  October,  1907 

July,  19(»9,  January,  1911,  January,  1913 


I]3Iea0ant 
J.  HORACE  MCFARLAND  COMPANY 
HARRISBURG  •  PENNSYLVANIA 


PREFACE 

MOST  works  on  irrigation  have  been  written 
from  the  legal  or  sociological  standpoint,  or  from 
that  of  the  engineer,  rather  than  from  the  cul- 
tural phases  of  the  subject.  The  effort  is  made 
here  to  present  in  a  broad  yet  specific  way  the 
fundamental  principles  which  underlie  the  methods 
of  culture  by  irrigation  and  drainage.  Distinc- 
tively engineering  principles  and  problems,  as  such, 
have  been  avoided,  and  so  have  those  of  plant 
husbandry.  The  aim  has  been  to  deal  with  those 
relations  of  water  to  soils  and  to  plants  which 
must  be  grasped  in  order  to  permit  a  rational 
practice  of  applying,  removing  or  conserving  soil 
moisture  in  crop  production.  The  immediately 
practical  problems,  from  the  farmer's,  fruit-grower's 
and  gardener's  standpoints,  with  the  principles 
which  underlie  them,  are  presented  in  as  con- 
crete and  concise  a  manner  as  appears  needful 
to  build  up  a  rational  practice  of  irrigation 
culture  and  farm  drainage  ;  and  the  effort  has 
been  to  broaden  the  conceptions  of  general  soil 

(v) 

267535 


vi  Preface 

management,  even  when  neither  irrigation  nor 
drainage  is  practiced. 

Great  pains  has  been  taken  to  personally 
inspect  the  irrigation  practices  of  both  humid  and 
arid  climates  in  this  country  and  in  Europe,  to 
gain  a  broader  view  of  essential  details,  and  to 
secure  suitable  illustrations,  which  are  presented 
largely  as  photo -engravings,  in  the  hope  of  getting 
closer  to  the  spirit  of  the  subject. 

Free  use  has  been  made  of  all  available  litera- 
ture on  the  subject,  and  credit  is  given  throughout 
the  body  of  the  text  to  various  writers  and 

works. 

P     H.    KING. 

UNIVERSITY  OF   WISCONSIN, 
March,  1899. 


CONTENTS 

INTRODUCTION  (pages  1-65) 
GENERAL  REMARKS  ON  THE  IMPORTANCE  OF  WATER 

PAGES 

Definition  of  irrigation  and  drainage  —  Importance  of  water 
in  crop  production  —  Plants  adapted  to  intermittent 
watering — Variation  in  the  capacity  of  soils  for  water — 
Adaptation  of  plants  to  soils  of  different  water  capacity 
— Variations  in  soils  and  in  rainfall  may  make  irrigation 
or  drainage  needful  —  Better  aeration  and  deeper  root 
feeding  in  arid  soils  —  Explanations  not  entirely  satis- 
factory    1-9 

The  Advantages  of  Abundant  Supply  of  Soil  Moisture. —  Large 
volumes  of  water  generally  needed  —  Part  played  by  water 
in  crop  production  —  Relation  to  plant  life  —  Relation  to 
soil  microbes  —  Rains  and  irrigation  may  start  formation 
of  nitrates  by  diluting  soil  moisture  —  Relation  of  drain- 
age to  development  of  nitrates  and  soil  fertility — Soil 
water  dissolves  ash  ingredients  of  plant-food — Water 
causes  oxygen,  carbon  dioxide  and  nitrogen  to  enter 
the  soil 9-15 

Water  only  One  of  the  Necessary  Plant- foods. —  Difference  in 
value  of  water  for  plant-food  —  More  water  used  than 
any  other  substance 15, 16 

Amount  of  Water  Used  by  Plants.—  Relation  of  climate  to 
water  used  —  Treatment  of  soil  affects  amount  of  water 
used  —  Irrigation  and  drainage  modify  amount  of  soil 
moisture — Apparatus  used  in  measuring  water  used  by 
plants  —  Aims  of  the  experiments  —  First  trials  with  oats, 
barley  and  maize  —  Field  results  with  maize  —  Changes 
of  soil  moisture  in  field  —  Experiments  with  oats  and 
barley  — Experiments  of  1893  to  1896. 16  38 

(vii) 


viii  Contents 

PAGES 

Variations  in  the  Amount  of  Water  Used  by  Plants.— Two 
years  compared  —  Field  and  plant-house  yields  compared 

—  Loss  of  water  in  a  saturated  air  —  Amount  of  water 
required  to  produce  one  ton  of  dry  matter 39-46 

The  Mechanism  and  Method  of  Transpiration  in  Plants.— 
Transpiration  and  breathing — Structure  of  barley  leaf  — 
Inevitable  loss  of  water  by  evaporation  makes  demands 
large — Amount  of  air  breathed  by  clover  to  secure  the 
needed  carbon  —  Changes  in  humidity  of  air  over  a  clover 
field — Assimilation  of  carbon  takes  place  only  in  sun- 
shine —  Breathing  pores  in  leaves  —  How  stomata  per- 
mit and  prevent  loss  of  water  —  Structure  of  breathing 
pores 46-54 

Mechanism  by  which  Land  Plants  Supply  Themselves  with 
Water. —  Part  played  by  roots  —  Essential  features  of 
roots  —  Only  the  newer  portions  active  in  absorbing 
moisture  —  How  water  is  taken  up  —  Kate  of  feeding 
slows  down  as  thickness  of  film  becomes  less  —  Root 
hairs  acid  and  may  hasten  solution  of  plant-food  —  Need 
of  great  extent  of  root  surface — Distribution  of  roots  in 
soil  —  How  roots  advance  through  soil — The  root-cap. . . .  54-65 

PART  I 

IRRIGATION   CULTURE 
CHAPTER  I 

THE  EXTENT  AND  GEOGRAPHIC  RANGE  OF  IRRIGATION 
(pages  66-90) 

The  Antiquity  of  Irrigation.— In  Egypt  —  In  Assyria  —  By 
the  Phoenicians  —  Early  Grecian  and  Roman  —  In  China 

—  In  Mexico  and  Peru 66-72 

Extent  of  Irrigation.— In  the  Po  valley  —  In  Sicily — In 
Spain  — In  France  —  In  Switzerland — In  Belgium  —  In 
Denmark — In  Austria-Hungaria  —  In  Bavaria  —  In  Eng- 
land —  In  India  —  In  Ceylon  —  In  Australia  —  In  other 


Contents  ix 

PAGES 

parts  of  Asia — In  Algeria  —  In  Egypt  —  In  Cape  Colony 
—  In  Madagascar  —  In  the  Hawaiian  Islands — In  Java  — 
In  South  America  —  In  the  Argentine  Republic  —  In 
Western  United  States — Amount  of  land  irrigated 72-89 

The  Climatic  Conditions  Under  which  Irrigation  Has  Seen 
Practiced. — Amount  of  rainfall  where  irrigation  has  been 
practiced  —  Distribution  of  rain  with  reference  to  the 
growing  season 89,  90 

CHAPTER  II 

THE  CONDITIONS  WHICH  MAKE  IRRIGATION  IMPERATIVE, 
DESIRABLE,  OR  UNNECESSARY  (pages  91-116) 

Objects  of  Irrigation.—  To  establish  right  moisture  relations 
— To  increase  fertility  —  To  change  texture  of  soil  —  To 
build  up  low  areas  —  For  sewage  disposal 91-94 

The  Least  Amount  of  Water  ichich  Can  Produce  a  Paying 
Crop — Importance  of  the  subject  —  Amount  of  water 
needed  for  wheat  —  Slow  rate  of  evaporation  from  dry 
soil  —  Average  yield  of  wheat  as  related  to  rainfall  — 
Dry  farming 95-101 

Like  Amounts  of  Rainfall  not  Equally  Productive. —  Differ- 
ences in  yield  and  in  rainfall  —  Causes  of  differences  . .  101-106 

Frequency  and  Length  of  Periods  of  Drought.—  Abundant 
watering  at  short  intervals  needful — Type  of  rain  dis- 
tribution -  Ineffective  rains — Length  of  rainfall  periods 
in  Wisconsin— Yield  of  crops  compared  with  rainfall  — 
Length  of  too  long  periods  of  no  rain — Yields  due  to 
rainfall  and  to  irrigation  compared 106-110 

Conditions  which  Modify  the  Effectiveness  of  Rainfall.—  In- 
fluence of  soil  texture — Amount  of  moisture  in  soil 
when  growth  is  checked  —  Loss  of  water  by  percolation 
— Rapid  percolation  chief  cause  of  poor  yields— Supple- 
mentary irrigation  helpful  on  light  lands— Topographic 
conditions  influencing  effectiveness — Sub-irrigation  may 
supplement  rainfall 110  116 


Contents 


CHAPTER  III 

THE  EXTENT  TO  WHICH  TILLAGE  MAY  TAKE  THE  PLACE 
OF  IRRIGATION  (pages  117-170) 

PAGES 

The  Insufficiency  of  Water  to  Irrigate  all  Cultivated  Lands. — 
Discharge  of  the  Mississippi  river — Mean  annual  run- 
off for  the  United  States  —  Proportion  of  cultivated 
fields  which  might  be  irrigated 117-120 

Most  which  may  be  Hoped  for  Tillage  in  the  Use  of  Water. — 
Do  soils  take  moisture  from  air  to  helpful  extent  f — 
Tillage  does  not  diminish  transpiration  in  plants,  and 
cannot  dispense  with  water 120, 121 

TJie  Amount  of  Rain  Needed  to  Produce  Maximum  Crops  in 
Humid  and  Sub-humid  Regions.— Acre-inches  required 
for  a  pound  of  dry  matter — The  amount  of  available 
rainfall  in  the  United  States  —  Effective  rainfall  of  13 
states — Theoretical  yields  which  may  be  expected 121-125 

The  Distribution  of  Rain  in  Time  Unfavorable  to  Maximum 
Yields. — Mean  yields  of  barley,  oats  and  maize  in  13 
states  —  Small  mean  yields,  due  to  unfavorable  dis- 
tribution of  rain 125-127 

Methods  of  Tillage  to  Conserve  Moisture  often  Ineffective.— 
Cultivation  inapplicable — Meadows  and  pastures — Mean 
yield  of  hay  in  13  states — Relation  of  yield  of  hay  to 
effective  rainfall  —  Tillage  methods  only  partly  appli- 
cable to  small  grains 127, 128 

Tillage  to  Save  Moisture  is  Chiefly  Effective  in  Saving  Winter 
and  Early  Spring  Rains. — Late  rains  largely  absorbed 
by  the  surface  three  inches  —  Roots  develop  close  to 
the  surface  in  late  summer 128,129 

Midsummer  and  Early  Fall  Crops  Difficult  to  Raise  without 
Irrigation. — Summer  rains  less  effective — Yields  of  sec- 
ond crop  clover— A  crop  of  barley  and  hay  the  same 
season..  .  129-131 


Contents  xi 

PAGES 

Fall  Plowing  to  Conserve  Moisture. — How  most  effective- 
Amount  of  moisture  saved — Most  important  in  sub- 
humid  climates— Applicable  to  orchards  and  small 
fruits 131-133 

Subsoiling  to  Conserve  Moisture. — Magnitude  of  the  effects 

—Duration  of  the  effects 133-138 

Explanation  of  Effects  of  Subsoiling. — Increases  water  ca- 
pacity of  soil  stirred— Decreases  the  capillary  conduct- 
ing power — Allows  the  water  to  enter  soil  more  deeply 
— Larger  per  cent  of  water  available  to  crops 139-142 

Earth  Mulches. — Conditions  modifying  effectiveness — Loses 
in  effectiveness  with  age — Other  mulches — Too  close 
pasturing  wasteful — Value  of.  surface  dressings  of  ma- 
nure— Harrowing  and  rolling  small  grains  after  they 
are  up 142-147 

Early  Tillage  to  Save  Moisture. — Amount  saved — Most 
effective  tools  —  Early  stirring  rather  than  early 
planting . .  147-151 

Danger  of  Plowing  Under  Green  Manures. — Catch  crops  in 

humid  and  sub-humid  climates 151-153 

Summer  Fallowing  in  Relation  to  Soil  Moisture 153,154 

Influence  of  Summer  Fallowing  on  Soil  Moisture  and   on 

Plant-food 154-157 

Old  Systems  of  Intertillage. —  Jethro  Tull's  method  — 
Hunter's  modification  —  The  Lois-Weedon  system  — 
Planting  and  tillage  to  utilize  the  whole  rainfall  — 
Distance  roots  of  corn  and  potatoes  spread  laterally— 
Distribution  of  moisture  in  potato  field— Lateral  feed- 
ing of  oats — Horse-hoeing  grain  a  form  of  summer 
fallowing : 157-163 

Frequency  of  Tillage  to  Conserve  Soil  Moisture.—  Should 
often  take  place  at  the  earliest  possible  moment — Dan- 
ger from  late  tillage 164,165 


xii  Contents 

PAGES 

The  Proper  Depth  of  Surface  Tillage  and  Ridged  and  Flat 
Cultivation. — Depth  of  early  tillage — Deep  ridges  objec- 
tionable— Ridge  cultivation  may  be  advisable  for  potato 
culture 165,166 

Rolling  in  Relation  to  Soil  Moisture. — Firming  the  surface 
to  establish  capillary  connection  with  the  soil  below — 
Rolling  may  warm  soil — Rolling  may  bring  water  to  the 
surface — The  press  drill 166,167 

Destructive  Effects  of  Winds.— Conditions  for  injury — De- 
structive effects  on  sandy  lands— Influence  of  groves 
and  hedgerows  on  evaporation — Protective  influence  of 
grass — The  value  of  hedges  in  windy  sections 168-170 

CHAPTER  IV 

THE  INCREASE  OF  YIELD  DUE  TO  IRRIGATION  IN  HUMID  CLIMATES 
(pages  171-195) 

Importance  of  the  Amount  and  Distribution  of  Water  in 
Potato  Culture,  and  the  Advantage  of  Irrigation  in  Cli- 
mates like  Wisconsin. — Time  and  method  of  planting — 
Amount  of  water  used — Differences  in  yield 171-175 

Effect  of  Supplementing  the  Rainfall  in  Wisconsin  for  Cab- 
bage Culture. — Method  of  planting — Weight  of  heads — 
Influence  on  yield  of  thick  and  thin  planting — Amount 
of  water  given  crop 175, 176 

Effect  of  Supplementing  the  Rainfall  with  Irrigation  on  the 

Yield  of  Corn. — Difference  in  yield  and  in  water  used. .  176-178 

Effect  of  Supplementing  the  Rainfall  with  Irrigation  on  the 

Yield  of  Clover  and  Hay 178,179 

A  Crop  of  Barley  and  a  Crop  of  Hay  the  Same  Season 179-181 

Effect  of  Supplementing  the  Rainfall  for  Strawberries 181 


Contents 


xui 


Closer  Planting  Made  Possible  by  Irrigation.—  Breathing 
room  in  the  soil  limited — Soil  temperature  lowered  by 
close  planting — Amount  of  sunshine  limited  —  Ten- 
dency to  lodge  when  planted  too  close — Possible  insuf- 
ficiency of  carbon  dioxide— Amount  of  carbon  used  by 
maize 181-187 

The  Maximum  Limit  of  Productiveness  for  Maize. — Mean 
weight  of  plants — Maximum  yields  computed — Observed 
yields  187-190 

Observed  Yields  of  Maize  per  acre,  Planted  in  Different 
Degrees  of  Thickness  and  with  Different  Amounts  of 
Water. — Yields  of  dry  matter— Yields  of  shelled  corn. .  190-193 

Influence  of  Thick  Seeding  and  Irrigation  on  the  Develop- 
ment of  the  Plant.—  Lengthening  of  the  nodes 193-195 

CHAPTER  V 

AMOUNT  AND  MEASUREMENT  OF  WATER  FOR  IRRIGATION 
(pages  196-221) 

The  Maximum  Duty  of  Water  in  Crop  Production 196-199 

Conditions  which  Modify  the  Amount  of  Water  Required  for 
Irrigation. — Peculiarities  of  crop— Character  of  soil — 
Character  of  subsoil — Character  of  rainfall — Frequency 
and  thoroughness  of  cultivation — Closeness  of  planting 
— Fertility  of  land— Frequency  of  applying  water 199-208 

Amount  of  Water  Used  in  Irrigation. — In  Italy — In  Spain 
and  France — In  Egypt — General  tables — Mean  amount 
—  For  sugar  cane  —  Highest  probable  duty,  table  — 
Bushels  of  grain  per  cubic  foot  of  water,  table 208-217 

Duty  of  Water  in  Mice  Culture 217,218 

Duty  of  Water  on  Water-meadows  219,220 

Duty  of  Water  in  Cranberry  Culture 220,221 


xiv  Contents 

CHAPTER  VI 

FREQUENCY,  AMOUNT  AND  MEASUREMENT  OF  WATER  FOR  SINGLE 
IRRIGATIONS  (page  222-247) 

PAGES 

Amount  of  Water  for  Single  Irrigations. — Soil  leaching  in 
humid  climates — Conditions  which  determine  the 
amount  of  water  used — Conditions  which  determine  the 
frequency  of  irrigation  222-224 

Capacity  of  Soils  to  Store  Water  under  Field  Conditions.— 
Amount  of  soil  moisture  when  growth  was  checked — 
Upper  and  lower  limits  of  best  amount — Amount 
needed  for  one  irrigation 224-227 

Depth  of   Eoot   Penetration. — Prune    on    Peach — Apple — 

Grape— Raspberry— Strawberry— Alfalfa  227-234 

Frequency  of  Irrigation. — Theoretical — For  wheat — For 
maize — For  clover,  alfalfa  and  meadows— For  potatoes 
—For  rice 234-239 

Measurement  of  Water. — Necessity — Advantages 239 

Units  of  Measurement. — Acre-inch — Acre-foot  —  Second- 
foot— Miner's  inch 239-241 

Methods  of  Measurement. — Time  division — Subdivision  of 

laterals — Use  of  divisors — Use  of  modules 241-247 


CHAPTER   VII 

CHARACTER  OF  WATER  FOR  IRRIGATION  (pages  248-268) 

Temperature  of  Water  for  Irrigation. — Best,  temperature — 
Danger  from  cold  water — Amount  soil  temperature  may 
be  lowered 248-251 

Fertilizing  Value  of  Irrigation  Water. — Amount  in  two  acre  - 

feet  251-253 

Sewage  Water  for  Irrigation. — On  Craigentinny  meadows — 

Healthfulness  of  milk  from  sewage  grass 253-258 


Contents 


xv 


The  Valu.e  of  Turbid  Water  in  Irrigation. — Rio  Grande — 

Po— Nile — Durance.    259,  260 

Improvement  of  Land  by  Silting. — Warping  or  colmatage — 

Silting  of  gravelly  soils 261-264 

Opportunities  for  Silting  in  Eastern  United  States. — In  Wis- 
consin and  Michigan — In  New  York  and  New  Jersey — 
In  the  South 264-266 

Alkali  Waters  not  Suitable  for  Irrigation. — Safe  and  unsafe 

alkali  waters 266-268 

CHAPTER   VIII 

ALKALI  LANDS  (pages  269-289) 

Characteristics  of  Alkali  Lands 269, 270 

Causes  of  Injuries  by  Alkalies. — Plasmolytic  effects — Toxic 

effects 270, 271 

Hoiv  Alkalies  Accumulate  in  the  Soil.  — By  capillarity— In 

marsh  soils  by  underflow 272-274 

Intensive  Farming  may  Tend  to  the  Accumulation  of  Alkalies.  274,  275 

Amount  of  Soluble  Salts  which  are  Injurious  in  Soils. — Con- 
clusions of  Plagniol — Of  Dehe>ain— Of  Gasparin — Of 
Hilgard— Plasmolytic  action 275-278 

Composition  of  Alkali  Salts. — In  California— In  Washington.  278-280 

Appearance  of  Vegetation  on  Alkali  Lands. — In  arid  regions — 

In  humid  regions 281-283 

Conditions  which  Modify  the  Distribution  of  Alkalies  in  Soil. 

—Tillage— Shading— Action  of  roots 283,  284 

Use  of  Land  Plaster  to  Destroy  Black  Alkali. — Hilgard 's 

conclusions 284,  285 

Kinds  of  Soil  which  Soonest  Develop  Alkali 286 

Correction  of  Alkali  Water  before  Use  in  Irrigation 287 

Drainage  Must  be  Ultimate  Remedy  for  Alkali  Lands 287-289 


xvi  Contents 

CHAPTER  IX 
SUPPLYING  WATER  FOR  IRRIGATION  (pages  290-328) 

PAGES 

Diverting  River  Waters. — Sirhind  canal — Kern  Island  canal- 
Dangers  from  seepage— Eedlands  system— Redwood 
pipe  line — Inverted  siphon — Redwood  flume — Cement 
flume — Cement  hydrants 290-304 

Diverting  Underground  Waters. — By  submerged  dams — By 

submerged  canals— By  tunnels 304,  305 

Diverting  Water  by  Tidal  Damming 306 

Diverting  Water  by  Power  of  the  Stream. — Undershot  wheels 
—Bucket  wheels — Turbines — Hydraulic  rams — Ram- 
ming engines— Siphon  elevator 306-310 

Utilizing  Storm  Waters  for  Irrigation 311,  312 

Wind  Power  for  Irrigation. — Record  of  experiments 312-316 

Water  Pumped  in  10-day   Periods. — Number   of   acres  a 

windmill  may  irrigate 316-318 

Necessary  Conditions  for  the  Highest  Service  with  a  Wind- 
mill.— Good  exposure — More  than  one  pump — Storage 
system 318, 319 

The  Use  of  Reservoirs. — Construction — Size  to  supply  given 

areas 320-323 

Pumping    Water  with  Engines. — Cost  with  gasolene — With 

steam— In  Egypt 324-327 

Use  of  Animal  Power  for  Lifting    Water  for  Irrigation. — 

Persian  wheel — Bucket  pump— Doon-  Shadoof 328 

CHAPTER  X 
METHODS  OF  APPLYING  WATER  IN  IRRIGATION  (pages  329-402) 

Principles   Governing  the    Wetting   of  Soils. — Influence  of 

texture— Effect  of  soil  becoming  dry 330-334 


Contents  xvii 

PAGES 

Principles  Governing  the  Puddling  of  Soils. — Character  of 

puddling — Bad  effects — Precautions  to  prevent 334-336 

Principles  Governing  the  Washing  of  Soils. — The  common 
mistake — What  constitutes  good  irrigation — Methods 
which  prevent  washing 337,  333 

Field  Irrigation  ~by  Flooding. — Two  different  types — Used 
most  where  intertillage  cannot  be  practiced — Flooding 
by  running  water — As  practiced  in  Colorado — Where 
slopes  are  steep — Where  fields  are  short — Flooding  by 
checks — Size  of  checks — Forming  checks— On  irregular 
slopes — Handling  the  water— Large  systems  -  Forming 
check  -ridges 338-350 

Fitting    the    Surface  for   Irrigation. — Leveling   devices— 

Shuart  land  grader — French  land  grader 351,  352 

Field  Irrigation  ~by  Furrows.— Adapted  to  intertillage  crops 
— Watering  before  planting — Irrigation  of  potatoes — 
Watering  alternate  rows— Lateral  spreading  of  water- 
Effect  on  yield  —Watering  sugar  beets  and  maize 352-359 

Water-meadows. — Laid  out  for  continuous  flow — System  at 
Salisbury,  England — In  Italy — In  Belgium— Mountain 
meadows 359-365 

Irrigation  of  Cranberries.—  Laying  out  the  marshes — Rapid 
flooding  and  draining — Irrigation  of  small  fields  by 
pumping 365—368 

Irrigation  of  Rice  Fields.— South  Carolina  system — Trunks 
— Germinating  the  rice — Dry  hoeing — Irrigation  after 
dry  growth  stage — Prevention  of  red  rice — Upland  irri- 
gation    368-373 

Orchard  Irrigation. — Furrow  method  best  —  Capillary 
spreading  of  water — Distributing  flumes — Foot  ditch — 
Watering  by  ring  furrows • 373-381 

Cultivation  after  Irrigation. —  The  cardinal  principle — 
Forms  of  orchard  cultivators — Importance  of  cultiva- 
tion in  humid  climates • 381-383 


xviii  Contents 

PAGES 

Small  Fruit  Irrigation. — Frequent  irrigation  needed  for 
strawberries — Watering  alternate  rows  to  facilitate 
picking 383,  384 

Garden  Irrigation. — Bed  irrigation — Bailing  system — Ridge 
and  furrow  method — Basin  flooding — At  Gennevilliers — 
At  San  Bernardino 384-391 

Irrigation  of  Lawns  and  Parks. — Inadequacy  of  spraying — 

Rainfall  of  humid  climates  not  usually  sufficient 391-390 

Sub -irrigation. — Not  economical  of  water — Water  not  ap- 
plied where  most  effective — Unequal  wetting  of  the 
soil— First  cost  heavy — May  be  applicable  in  certain 
cases 396-402 

CHAPTER  XI 
SEWAGE  IRRIGATION  (pages  403-414) 

Objects  Sought  in  Sewage  Irrigation.—  Destruction  of  or- 
ganic products — Utilization  of  fertility  carried 403 

Climatic  Conditions  Favorable  to  Sewage  Irrigation.— Warm 
climates  best  suited — Cold  soils  chiefly  filters — Large 
area  required  for  winter  handling 404,  405 

Process  of  Sewage  Purification  by  Irrigation  and  Intermit- 
tent Filtration.— Essential  conditions  —  Effect  of  too 
rapid  application 405,  406 

Soils  Best  Suited  to  Sewage  Irrigation. — Lighter  loams  and 

sandy  soils — Any  soil  adapted  if  area  is  sufficient 406 

Desirability  of  Wider  Agricultural  Use  of  Sewage  in  Irriga- 
tion.— Examples  of  valuable  results — Sections  of  country 
specially  adapted  to  it 406-409 

Crops  Suited  to  Sewage  Irrigation. — Grass,  most  generally 
— Soil  for  intertillage  crops  fertilized  by  winter  irriga- 
tion— Potatoes  at  Croyden — May  injure  grass  if  applied 
in  winter 409-413 

Influence  of  Sewage  Upon  the  Health. — At  Gennevilliers — 

Purity  of  effluent  compared  with  well  water 413,  414 


Contents  xix 

PART  II 
FARM   DRAINAGE 

CHAPTER  XII 

PRINCIPLES  OF  DRAINAGE  (pages  415-466) 

PAGES 

The  Necessity  for  Drainage. —  Removal  of  injurious  salts  — 

Better  soil  ventilation — Makes  the  soil  more  firm 416, 417 

The  Demands  for  Air  in  the  Soil.— Supply  of  free  oxygen — 

To  lessen  denitrification — Facilitates  chemical  changes.  .  418,419 

How  Drainage  Ventilates  the  Soil. — Permits  roots  and  bur- 
rowing animals  to  go  deeper  —  Develops  shrinkage 
checks  —  Favors  granulation  of  soil  —  Barometric  and 
temperature  changes — Suctional  effect  of  rains 419-421 

Too  Thorough  Aeration  of  the  Soil. — Leads  to  destruction  of 

humus — Care  of  open  soils 421,422 

Drainage  Increases  the  Supply  of  Available  Moisture  for 
Crops. —  Deeper  root  penetration — Stronger  capillarity 
—  Stronger  nitrification — Deeper  ground  water  more 
available „ 422,423 

Soil  Made  Warmer  by  Drainage. —  By  lessening  surface 
evaporation  —  By  lowering  specific  heat  —  Observed 
differences  of  temperature 423-425 

Importance  of  Soil   Warmth. —  Relation  to  germination  — 

Hastens  development  of  plant-food 425-428 

Conditions  under  which  Land  Drainage  Becomes  Desirable. — 
Lands  subject  to  frequent  overflow — Lands  with  strong 
underflow  near  surface — Tidal  plains — Flat  lands  with 
heavy  subsoils 428 

Origin  of  Ground  Water  and  its  Relation  to  the  Surface. — 
Vertical  movement  of  rains  —  Surface  of  ground  water 

Lines  of  flow — Growth  of  rivers 429-435 


xx  Contents 

PAGES 

Kate  at  which  Ground  Water  Surface  Rises  away  from  the 
Drainage  Outlet. —  In  tile-drained  field — Where  not 
tile-drained 435,  436 

Depth  at  which  Drains  should  be  Placed. —  Kind  of  crop  — 
Seasonal  changes  of  ground  water — Character  of  soil  — 
Distance  between  drains 436,  437 

Distance  Between  Drains. — Texture  of  subsoil  —  Depth  of 
drain— Interval  of  time  between  rains  or  irrigations — 
Climatic  conditions 437, 442 

Kinds  of  Drains .—  Closed  —  Open  —  Stone  —Wood  —  Brick 

—Peat— Tile— Cement 443-445 

How  Water  Enters  Drains. — Rate  through  the  walls  — 
Through  the  joints  —  Care  in  making  close  joints  —  Use 
of  collars 445, 446 

Fall  or  Gradient  of  Drains. — Highest  practicable — Selecting 
course  for  the  main — Care  in  laying  to  grade — Change 
of  grade— Use  of  silt  well 447-449 

Size  of  Tile. — No  specific  statement  possible  except  where 
all  details  are  known  —  Size  increases  with  length  — 
Seldom  smaller  than  three  inches  in  diameter — Example 
of  sizes  and  lengths " 449-452 

Outlet  of  Drains. — Should  have  a  clear  fall  —  Precautions 
against  injury  from  frost  —  Connecting  laterals  with 
mains 453,  454 

Obstructions  to  Drains. — From  roots—  Kinds  of  trees  most 

troublesome 455,  456 

Laying  Out  Systems  of  Tile 456-459 

Intercepting  the  Underflow  from  Hillsides 459,  460 

Draining  Sinks  and  Ponds. — By  intercepting  surface  drain- 
age—By subdrainage- 460-462 

The  Use  of  Trees  in  Drainage 462,  463 


Contents  xxi 

PAGES 

The  Use  of  the  Windmill  in  Drainage. — Arrangement   for 

winter  pumping — Subirrigation  as  an  adjunct 463, 464 

Lands  which  must  be  Surface  Drained. — Ancient  lake  bot- 
toms underlaid  with  clay  —  Sections  where  there  are  no 
natural  surface  outlets 464-466 

CHAPTER  XIII 

PRACTICAL  DETAILS  OF  UNDERDRAINING  (pages  467-492) 

Methods  of  Determining  Levels. — Kinds  of  levels 469-471 

Leveling  a  Field. — Making  contour  map — Using  the  level. .  471-473 

Location  of  Mains  and   Laterals.—  Securing  the  greatest 

fall 474  476 

Staking  Out  Drains.  —  Grade  pegs 476, 477 

Determining  the  Grade  and  Depth  of  Ditches. — Method  of 

marking  stakes  for  use  of  ditchers 477-481 

More  than  One  Grade  on  the  Same  Drain 481 

Digging  the  Ditch.  — Tools  used  —  Method  of  procedure  — 

Methods  of  filling 481-488 

Cost  of  Underdraining . — For  mains— For  laterals 489-491 

Peat  Marshes  . .  491,492 


IRRIGATION  AND  DRAINAGE 


INTRODUCTION 

GENERAL  REMARKS  ON  THE  IMPORTANCE  OF  WATER 

THE  watering  of  land,  which  is  irrigation,  and  the 
withdrawal  of  such  part  of  that  water  as  does  not 
evaporate,  which  is  land  drainage,  are  two  methods, 
one  the  opposite  of  the  other ;  but,  looked  at  in  the 
broadest  sense,  both  are  natural,  and  each  is  as  old 
as  the  time  when  the  rains  descended  upon  the  first 
lands  which  rose  above  the  ocean's  level.  The  periodic 
watering  and  draining  of  the  earliest  rock  fragments 
which  covered  the  earliest  lands,  and  which  came  to 
be  the  earliest  soils,  constituted  at  once  the  most 
primitive,  the  most  profound,  and  the  most  persis- 
tent environment  to  which  all  forms  of  land -life 
have  been  forced  to  adapt  themselves. 

Since  the  very  earliest  forms  of  life  probably  came 
into  being  in  the  water,  and  were  composed  in  large 
measure  of  it,  it  is  not  strange  that  we  yet  know  of 
no  forms  which  can  live  without  water,  and  to  which, 
indeed,  water  is  not  the  most  fundamentally  important 
substance  and  food.  It  is  so,  not  more  because  it 
makes  up  so  large  a  part  by  weight  of  all  living  and 

A  (1) 


£v:>  Irrigation   and    Drainage 

growing  parts  of  plant  life,  than  because  it  is  the 
medium  in  which  the  transformation  of  the  crude 
materials  into  assimilable  food -products  takes  place, 
and  through  and  by  means  of  which  these  products 
are  transported  to  their  destinations  at  the  various 
points  of  growth.  It  is  only  when  we  fully  appreciate 
the  important  role  played  by  water  in  crop  production, 
that  we  are  in  position  to  see  how  necessary  to  large 
yields  is  the  right  amount  of  water  at  the  right  time, 
and  thus  be  led  to  insure  to  our  crops  a  sufficient 
irrigation  and  an  adequate  drainage. 

Since  the  falling  of  rain  upon  soils  has  always 
been  intermittent  in  its  character,  and  during  the  in- 
tervals of  fair  weather  a  part  of  the  water  so  given 
to  the  soil  has  been  lost  by.  drainage,  land  vegetation, 
during  its  evolutionary  stages,  has  become  fitted  to  do 
its  best  work  when  the  soil  is  watered  once  in  about 
so  often,  and  when  that  soil  retains  a  certain  amount 
of  the  rain  which  falls.  But  the  intervals  between 
rains  in  almost  all  countries  are  irregular  in  length, 
and  the  amount  of  rain  which  falls  at  one  time  also 
varies  between  very  wide  limits,  so  that  in  many  if 
not  in  the  majority  of  climates,  those  seasons  are  rare 
indeed  when  a  crop  can  be  carried  to  maturity  with 
the  soil  containing  at  all  times  the  best  amount  of 
moisture.  This  being  true,  there  will  occur  times  with 
almost  all  soils  when  they  would  give  larger  yields  if 
they  could  be  artificially  irrigated  or  artificially  drained, 
according  as  the  period  is  one  of  deficient  or  of  exces- 
sive rain. 

But  not  all  soils  are  alike  in  their  capacity  for  re- 


Soil    Texture   in   Relation   to   Rainfall  3 

tainirig  moisture  and  of  permitting  it  to  drain  away, 
and  this  being  true,  under  one  and  the  same  conditions 
of  rainfall  one  field  might  be  benefited  by  irrigation 
while  another  one  would  profit  by  better  drainage. 

It  is  this  fact  of  varying  capacity  of  soils  to  store 
water  for  given  periods  of  time  that,  in  the  long  strug- 
gle for  existence  and  of  fitting  and  refitting  among 
plants,  has  led  to  the  evolution  of  certain  species 
which  can  thrive  best  in  a  soil  of  coarse  texture,  re- 
taining but  small  amounts  of  water  for  any  length  of 
time,  while  other  species  have  become  adapted  to  the 
soils  of  finer  texture  and  higher  water  capacity.  This 
is  a  fact  of  fundamental  importance,  not  only  in  decid- 
ing what  crops  may  be  grown  in  a  given  soil,  but 
whether  or  not  it  will  be  desirable  to  irrigate  such 
lands  beyond  the  natural  rainfall. 

A  soil  of  fine  texture  is  spoken  of  as  the  best  grass 
land,  for  example  ;  but  this  has  reference,  in  a  very 
large  degree,  to  a  certain  amount  and  frequency  of 
rainfall,  which  chances  to  be  such  as  to  maintain  for 
the  grasses  the  amount  of  water  in  the  soil  under 
which  they  have  become  accustomed  to  grow  best.  If 
there  were  another  soil  in  the  same  locality,  of  similar 
composition  but  of  coarser  texture,  and  so  of  smaller 
water  capacity,  it  is  most  probable  that  this  soil  would 
be  converted  into  equally  good  grass  land,  giving  just 
as  large  or  even  larger  yields  per  acre,  if  only  the 
natural  rainfall  were  supplemented  by  artificial  irri- 
gation, so  as  to  hold  the  water  of  the  soil  up  to  that 
quantity  which  the  grass  has  become  accustomed,  by 
long  breeding,  to  use. 


4  Irrigation   and    Drainage 

Then,  again,  on  the  other  hand,  the  soil  which  for 
a  given  climate  is  so  close-grained  that  it  does  not 
drain  sufficiently  between  rains  to  leave  it  dry  enough 
for  those  crops  which  have  become  accustomed  to  the 
smaller  water  capacity  of  the  coarser  soils,  may  be  all 
right  for  the  dry -soil  crop,  provided  it  occurs  in  a 
locality  of  smaller  or  less  frequent  rainfall.  Or,  again, 
in  the  region  of  heavier  rainfall,  this  soil  may  be  fitted 
for  the  dry-soil  crop  by  thorough  under-draining,  when 
the  lines  of  tile  are  placed  close  enough  to  draw  down 
the  water  to  a  sufficiently  low  point  to  leave  the  soil 
with  the  amount  of  moisture  which  is  suited  to  the 
crop  in  question. 

Another  soil  may  be  very  deep  and  exceptionally 
well  aerated,  on  account  of  its  peculiar  texture,  so 
that  the  roots  of  cultivated  crops  easily  penetrate  it  to 
much  greater  depths  than  is  possible  in  the  closer, 
more  compact,  non-aerated  subsoils  of  other  localities. 
When  this  is  the  case,  as  appears  often  to  be  true 
in  arid  and  semi -arid  climates,  notably  in  parts  of 
the  San  Joaquin  Valley,  in  California,  the  smaller  rain- 
fall of  the  winter  season  penetrates  the  soil  so  deeply, 
and  returns  to  the  surface  by  capillarity  so  slowly,  that 
fair  and  even  large  crops  are  often  raised  on  these 
soils  without  artificial  irrigation,  yet  not  a  drop  of 
rain  may  fall  upon  the  land  from  May  first  to  Septem- 
ber. So  different  are  the  conditions  in  humid  soils,  like 
those  of  the  eastern  United  States,  that  even  a  period 
of  ten  days  without  rain,  especially  if  it  occurs  in  the 
height  of  the  growing  season,  is  sure  to  bring  marked 
distress  even  to  field  crops  like  maize. 


Apparently  High  Service  of    Water  5 

One  of  the  most  striking  features  of  the  arid  sec- 
tions of  the  United  States,  which  attracted  the  writer's 
attention  during  his  travels  through  the  West,  was  this 
apparently  greater  service  of  water  in  crop  production 
than  is  realized  in  the  more  humid  climate  of  the  east- 
ern section  of  this  country.  Reasoning  from  general 
principles,  one  is  naturally  led  to  anticipate  that  in  an 
exceptionally  dry  atmosphere  and  under  a  clear  sky, 
such  as  we  have  in  the  western  United  States,  the  rate 
of  evaporation,  both  from  soil  and  vegetation,  would 
be  exceptionally  rapid,  and  hence  that  enormous  quan- 
tities of  water  would  be  required  in  crop  production, 
when  compared  with  the  demands  of  crops  under  more 
humid  conditions. 

Such,  however,  does. not  appear  to  be  the  case,  and 
it  is  this  fortunate  relation  which  makes  it  possible 
for  larger  areas  to  be  placed  under  irrigation  with  the 
limited  amounts  of  water  than  would  be  possible  were 
the  conditions  of  the  soil  more  like  those  of  humid 
climates. 

It  is  not  easy  to  assign  a  thoroughly  satisfactory 
set  of  reasons  for  this  marked  difference  without  a 
more  detailed  study  of  the  field  conditions  than  has 
yet  been  made.  It  seems  quite  probable,  however,  that 
prominent  among  the  reasons  to  be  assigned  for  these 
differences  is  the  one  to  which  reference  has  already 
been  made :  namely,  the  texture  of  the  soil,  which 
allows  the  water  to  distribute  itself  evenly  and  rela- 
tively deep  in  the  soil,  and  it  does  not  return 
readily  and  rapidly  by  capillarity  to  the  surface  to  be 
lost. 


6  Irrigation   and    Drainage 

In  passing  south  from  San  Francisco,  through  Lath- 
rop,  Merced  and  Fresno,  to  Bakersfield,  in  California, 
we  pass  across  a  long  stretch  of  country  where  there 
is  at  present  relatively  very  little  irrigation,  and  yet 
through  all  of  the  country  north  of  Merced  wheat  has 
been  extensively  grown,  and  during  the  early  years, 
when  the  soil  was  new,  large  yields  per  acre  have  been 
realized  without  irrigation,  the  crop  depending  upon 
the  rain  which  falls  during  the  rainy  season  of  winter 
and  sinks  into  the  soil,  to  be  later  used  by  the  deeper 
feeding  roots.  In  discussing  the  matter  with  Professor 
Hilgard,  he  informed  me  that  the  roots  of  crops 
penetrate  these  soils  much  more  deeply  than  is  normal 
to  them  under  other  conditions,  and  that  some  plants, 
when  brought  here,  really  change  their  habits  of  root 
growth  through  a  dying  off  of  the  normal  surface 
feeders  on  account  of  an  insufficiency  of  moisture  in 
the  upper  layers. 

Professor  Hilgard  further  informed  me  that  over 
much  of  the  state  of  California  the  rains  only  wet 
down  a  relatively  short  distance,  and  that  beneath  this 
zone  of  moistened  soil  the  balance  is  often  almost 
air -dry,  extending,  in  certain  cases  which  have  come 
under  his  observation,  to  depths  as  great  as  forty  feet. 
Where  «such  conditions  as  these  exist  there  is,  of 
course,  no  possibility  of  crops  deriving  a  supply  of 
moisture  through  natural  sub  -  irrigation  from  waters 
from  the  foothills  or  higher  mountain  masses  which 
rise  above  the  plains. 

My  own  observations  on  the  soils  of  humid  cli- 
mates convince  me  that  the  zone  of  dry  soil  to  which 


Apparently   High   Service  of   Water  7 

reference  has  been  made  must  act  as  a  powerful  ad- 
junct in  the  retardation  of  both  capillary  and  gravi- 
tational movements  of  water  below  the  reach  of  deep 
root  feeding ;  and  if  this  is  true,  practically  all  loss  of 
water  by  downward  percolation  is  prevented,  .and  the 
whole  rainfall  not  lost  by  surface  evaporation  becomes 
available  for  crop  production. 

There  is  another  condition,  brought  about  by  the 
presence  of  the  layer  of  air  -  dry  soil  beneath  the 
moisture -bearing  zone,  which  in  humid  regions  only 
exists  in  exceptional  localities,  and  which  may  have  an 
important  influence  in  making  a  larger  part  of  each 
year's  rainfall  available  for  crop  production.  I  refer 
to  the  possibility  of  the  large  amount  of  air  stored  in 
the  air- dry  soil  beneath  the  moist  layer  contributing 
to  deep  soil  breathing.  By  slow  diffusion  upward,  and 
by  movements  induced  by  changes  in  atmospheric  pres- 
sure, the  roots  may  be  supplied  with  oxygen  from  be- 
low as  well  as  from  above,  and  thus  have  their  feed- 
ing depth  lowered  on  this  account  beyond  what  is 
usual  in  humid  soils.  So,  too,  it  appears  to  be  quite 
possible  that  nitrification  and  other  biologic  processes 
may  be  permitted  to  go  forward  under  these  condi- 
tions, when  in  humid  soils  they  are  largely  prohibited 
for  lack  of  sufficient  aeration. 

These  suggestions,  however,  do  not  appear  to  offer 
an  adequate  explanation  of  the  ability  of  crops  to 
reach  maturity  in  the  arid  soils  of  the  West  without 
irrigation,  when  there  is  no  rain  for  such  long  inter- 
vals ;  for,  as  we  approached  Merced  from  the  north,  a 
very  sandy  belt  of  land  was  passed  which  was  white 


8  Irrigation   and    Drainage 

and  glistening  in  the  sun,  and  which  drifted  as  badly 
as  much  of  apparently  similar  land  in  Wisconsin,  and 
yet  on  these  coarse  sands  wheat  was  being  harvested 
which  would  give  larger  yields  than  would  be  expected 
on  such  lands  in  Wisconsin  with  a  summer  rainfall 
of  not  less  than  ten  inches.  But  here  the  crop  had 
stood  and  matured  from  early  May  until  the  end  of 
July  without  irrigation  and  without  rain.  One  is  led 
to  question  whether  it  may  not  be  true  that,  under 
the  stress  of  such  arid  conditions  of  both  atmosphere 
and  soil,  plants  of  some  kinds  may  develop  a  texture 
of  a  closer  nature,  with  fewer  and  smaller  breathing 
pores,  and  thus  reduce  the  loss  of  moisture  Ihrough 
their  surfaces  much  below  what  is  normal  to  the  same 
species  under  more  humid  conditions  of  soil  and  atmos- 
phere. Such  a  question  could,  of  course,  readily  be 
settled  by  a  proper  comparative  study  of  tissues  de^ 
veloped  under  the  two  conditions  ;  but,  so  far  as  we 
know,  it  has  not  yet  been  done.  It  should  be  said, 
however,  in  this  connection,  that  the  seemingly  greater 
service  of  water  to  which  reference  is  here  made  may 
be  more  apparent  than  real.  The  climate  of  the  region 
being  warm,  and  wheat  being  sown  from  the  begin- 
ning of  the  rainy  season  in  November  until  the  end 
of  January,  there  is  much  time  for  the  crop  to  germi- 
nate, and  to  get  its  root  system  thoroughly  established 
in  the  ground,  and  to  have  made  a  very  considerable 
growth,  before  the  close  of  the  rainy  season  early  in 
May.  There  are  left,  then,  only  the  months  of  May 
and  June  during  which  the  crop  must  complete  its 
growth  without  rain.  It  is  true  that  this  is  a  long 


Advantages   of  Abundant   Moisture  9 

period,  and  in  humid  climates,  where  the  growth  of 
vegetation*  can  only  begin  in  March  or  April,  even 
though  the  rainfall  were  the  same  as  in  the  San  Joaquin 
Valley,  crops  like  wheat  could  not  be  matured  ;  and  it 
is  quite  possible  that  this  would  also  be  true  of  the 
country  in  question  did  it  have  an  ice-bound  winter. 

In  the  vicinity  of  Fresno,  California,  where  a  large 
acreage  of  raisin  grapes  are  grown  on  a  sandy  loam, 
generally  without  irrigation,  it  is  the  belief  of  many 
of  the  growers  that  their  vineyards  derive  not  a  little 
moisture  through  a  seepage  from  the  canals  and  ditches 
of  the  district,  whose  waters  are  more  generally  used 
in  the  irrigation  of  alfalfa  ;  but,  as  many  of  these 
vineyards  are  considerable  distances  from  both  canals 
and  ditches,  it  is,  perhaps,  more  probable  that  the 
grapes  survive  through  extremely  deep  and  wide  root- 
feeding  and,  perhaps,  small  foliage  evaporation.  It  is 
the  naturally  small  water  capacity  of  the  Fresno  soils, 
and  those  referred  to  near  Merced,  which  makes  it  so 
difficult  to  understand  how,  even  with  very  wide  and 
deep  root -feeding,  moisture  enough  could  be  gathered 
to  maintain  growth  and  carry  a  crop  to  maturity 
without  rain  during  the  summer  season,  and  without 
irrigation . 


ADVANTAGES    OF   AN   ABUNDANT    SUPPLY   OF 
SOIL  MOISTURE 

While  there  are  such  cases  as  those  cited  above, 
in  which  plants  appear  to  thrive  and  to  produce  fair 
yields  with  relatively  small  amounts  of  water,  yet  it 


10  Irrigation   and    Drainage 

is  a  matter  of  universal  experience  in  humid  climates 
that  on  clayey  soils  heavy  protracted  spring  rains  con- 
tribute more  to  the  production  of  large  crops  of  grass 
than  all  the  manure  which  farmers  can  put  upon  their 
lands,  and  that  with  dry  springs  fertilizers,  of  what- 
ever sort  and  however  applied,  are  of  but  little  avail. 
So,  too,  four  weeks  of  copious,  timely,  warm  rains  .fall- 
ing upon  fields  of  potatoes  after  the  tubers  begin  to 
set,  and  of  corn  after  the  tassels  and  silk  begin  to 
form,  are  certain  to  be  followed  by  enormous  yields, 
even  when  the  soil  is  not  rich,  unless  frost  or  disease 
intervenes.  On  the  other  hand,  let  the  tuber  and  grain- 
forming  period  of  these  crops  be  one  of  drought,  and 
it  is  only  those  soils  which  are  most  retentive  of  mois- 
ture, and  which  have  been  most  skillfully  handled,  that 
are  able  to  mature  even  moderate  yields,  though  the 
land  be  very  rich. 

What,  then,  do  warm  spring  and  summer  rains  and 
warm,  sweet  irrigation  waters  do  in  the  soil  which  con- 
tributes so  much  to  plant  growth  ?  In  the  first  place, 
it  is  only  through  the  soil,  where  very  extensive  absorb- 
ing surfaces  of  root  hairs  are  developed,  that  plants 
are  able  to  obtain  the  very  large  amounts  of  water 
they  need  for  food  *and  for  the  maintenance  and  carry- 
ing forward  of  the  physiological  processes  which  are 
associated  with  plant  growth. 

But  it  is  not  alone  for  the  crop  which  is  being  grown 
upon  the  ground  that  water  is  needed  in  the  soil ;  for 
it  must  never  be  forgotten  that  there  are  living  within 
the  dark  recesses  of  the  soil  organisms  of  various  kinds 
upon  whose  normal  and  vigorous  activity  depends,  in 


Advantages   of  Abundant   Moisture  11 

a  high  degree,  the  magnitude  of  the  specific  crop  which 
is  to  be  harvested.  The  germs  which  react  upon  the 
dead  organic  matter  in  the  soil,  converting  it  into 
ammonia,  the  germs  which  change  the  ammonia  into 
nitrous  acid,  and  the  germs  which  transform  the  nitrous 
acid  into  nitric  acid, — which  is  the  real  nitrogen  supply 
of  most  of  the  higher  plants, —  each  and  all  are  depend- 
ent for  their  proper  activity  upon  the  right  amount  of 
moisture  in  the  soil.  Then,  there  are  those  symbiotic 
forms  of  lowly  organisms  whose  great  mission  it  is 
to  take  the  free  nitrogen  from  the  air  and  compound 
it  into  such  forms  as  shall  leave  it  available  for  the 
higher  plants,  and  which,  like  all  other  forms  of  life, 
must  have  water  and  to  spare  if  they  are  to  perform 
their  work.  Let  the  water  content  of  any  soil  be 
reduced  below  a  certain  amount,  and  all  of  these  vital 
processes  are  inevitably  slowed  down  ;  let  it  be  reduced 
to  a  still  lower  degree,  and  the  whole  line  is  at  a  com- 
plete standstill. 

Now,  in  humid  regions,  where  the  subsoils  are  much 
of  the  time  water -logged,  and  where,  as  a  consequence 
of  this,  there  is  but  little  soil  ventilation,  the  plant- 
food  builders  to  which  reference  has  just  been  made 
are  all  of  them  forced  into  a  thin  zone  close  to  the 
surface  of  the  ground,  where  their  work  must  all  be 
done  ;  but  if  this  surface  zone  is  allowed  to  become 
dry,  then  the  nitrogen -supplying  processes  must  come 
to  a  standstill,  and  the  crop  which  is  growing  above 
the  ground  must  have  its  growth  checked,  even  though 
it  has  put  its  roots  down  into  the  subsoil  where  mois- 
ture for  its  own  purposes  may  be  had,  Indeed,  we  may 


12  Irrigation    and    Drainage 

well  believe  that  one  of  the  chief  causes  which  has  led 
the  higher  plants  to  send  their  roots  foraging  so  deeply 
into  the  ground  is  this  great  need  of  water  in  the  sur- 
face layer,  where  the  nitrogen  suppliers  dwell,  and  for 
the  express  purpose  of  not  drawing  upon  this  supply 
too  extensively,  and  thus  leaving  the  surface  soil  to 
become  too  dry.  It  is  true  that  when  heavy  rains 
come,  or  when  irrigation  waters  are  applied  which  lead 
to  the  percolation  of  water  downward,  the  nitrates 
which  have  been  formed  at  and  near  the  surface  are 
dissolved  and  more  or  less  completely  washed  more 
deeply  into  the  ground,  where  the  deep -running  roots 
are  in  position  to  take  advantage  of  them  and  prevent 
their  being  lost ;  and  thus  a  double  gain  is  secured. 

Let  us  call  attention  to  another  important  principle. 
In  the  soils  which  have  been  highly  manured,  or  which 
are  naturally  well  supplied  with  organic  matter  ready 
for  decay,  large  amounts  of  nitrates  are  rapidly  formed. 
Under  such  conditions  the  moisture  which  invests  the 
soil  grains  rapidly  approaches  saturation,  and  finally 
reaches  a  point  when  it  is  carrying  so  many  salts  in 
solution  that  the  water  is  no  longer  suitable  for  the 
use  of  the  germs  which  have  given  rise  to  the  salts, 
and  their  activities  are  on  this  account  brought  to  a 
standstill.  But  let  a  rain  come  which  produces  perco- 
lation, or  let  the  field  be  irrigated  sufficiently  to  pro- 
duce the  same  effect,  and  at  once  the  salts  which  have 
been  inhibiting  the  nitrate -forming  process  are  washed 
out  and  a  fresh  supply  of  water  is  left,  which  at  once 
becomes  a  stimulus  for  increased  activity,  while  the 
ready -formed  salts  containing  nitric  acid  are  carried 


Fertility   Influenced   by  Drainage  13 

to  a  lower  level,  where  they  may  be  taken  up  by  the 
deeper -feeding  roots.  Here,  then,  we  are  led  to  see 
one  of  the  ways  in  which  water,  applied  at  the  sur- 
face at  opportune  times,  acts  as  a  wonderful  stimulus 
to  plant  growth. 

If,  now,  we  turn  from  the  irrigation  to  the  drain- 
age side  of  the  same  problem,  we  shall  see  in  another 
way  how  fundamentally  important  this  principle  is. 
Let  a  soil  be  inadequately  drained,  and  the  roots  of 
the  plants  will  be  forced  to  occupy  the  surface  soil, 
for  they  cannot  abide  in  the  water -logged  region. 
Then,  if  heavy  rains  come  and  percolation  results,  all 
of  the  unused  nitrates  which  may  have  been  in  the 
soil  at  the  time  are  at  once  washed  below  the  roots, 
and  perhaps  entirely  lost  to  the  crop.  But,  on  the 
other  hand,  if  the  soil  had  been  properly  drained,  so 
that  the  roots  of  the  crop  could  have  been  two,  three 
or  four  feet  below  the  surface,  then,  as  has  been  pointed 
out,  the  nitrates  would  have  been  washed  to  the  roots, 
where  they  would  have  become  at  once  available. 
Then,  too,  when  a  dry  period  comes,  with  all  the  life 
processes  going  on  in  the  soil  confined  close  to  the 
surface,  the  great  demand  for  water  from  the  roots 
forces  them  at  once  to  so  completely  dry  out  the  sec- 
tion they  occupy  that  a  violent  check  is  at  once  put 
both  upon  the  plant  itself  and  upon  all  the  food-form- 
ing processes  in  the  soil ;  for,  under  these  conditions, 
it  is  usually  impossible  for  capillarity  to  keep  pace 
with  the  loss  of  water  from  above,  and  the  soil  quickly 
becomes  too  dry. 

So  far  we  have  been  speaking  of  the  importance  of 


14  Irrigation   and    Drainage 

water  in  the  soil  to  the  direct  vital  processes  which 
are  going  on  there  whenever  steady  growth  is  taking 
place.  But  there  are  other  processes  which  are  purely 
physical,  to  which  attention  needs  to  be  called  before 
we  have  brought  into  view  the  full  line  of  operations 
to  which  this  great  agent,  water,  leads. 

Other  plant-foods, —  those  which  contain  the  phos- 
phoric acid,  potash,  lime,  magnesia,  iron  and  sulfur,— 
must  be  taken  from  the  inert  solid  form  in  the  soil 
into  solution  in  water  before  they  can  be  of  any  service 
in  plant  growth,  and  this  is  another  of  the  important 
roles  which  water  has  to  play  in  the  life  processes  of 
the  soil.  Then,  too,  all  water  used  in  irrigation,  and 
even  rain  water,  contains  larger  or  smaller  quantities 
of  plant -food,  either  directly  in  solution  or  borne  in 
suspension,  which  adds  so  much  to  the  fertility  of  the 
soil  itself. 

So,  too,  all  waters  which  have  been  exposed  to  the 
atmosphere  have  become  charged  with  oxygen,  carbon ic 
acid  and  nitrogen,  which  they  carry  with  them  into 
the  soil,  and  these  always  aid,  in  one  way  or  another, 
both  the  physical  and  the  life  processes  which  make 
for  fertility  of  the  land.  And,  again,  when  a  large 
volume  of  warm  water  falls  upon  or  is  applied  to  the 
soil,  and  it  sinks  deeply  into  it,  it  carries  with  it  not 
only  its  own  warmth,  but  also  the  heat  which  it  may 
have  absorbed  from  the  surface  of  the  ground  ;  and 
this  warmth,  carried  deeply  into  the  ground,  makes 
the  root  action  stronger  and  at  the  same  time  increases 
the  rate  of  solution  of  plant -food  from  the  soil  grains. 
When  we  have  made  this  brief  survey  of  what  warm 


Water   only    One   of  the   Necessary   Plant -foods   15 

rains  and  sweet  irrigation  waters  do  in  the  soil,  we 
may  not  be  surprised  to  see  the  large  yields  of  grass 
or  of  potatoes  or  corn  it  is  capable  of  helping  the 
soil  and  the  sunshine  to  bring  forth  as  the  product 
of  a  summer's  work. 


WATER  ONLY  ONE  OF  THE  NECESSARY  PLANT -FOODS 

In  view  of  the  facts  which  have  just  been  pre- 
sented, it  is  not  at  all  strange  that  the  ancient  Egyp- 
tian and  Grecian  philosophers,  with  their  lack  of  exact 
knowledge  and  under  their  arid  climatic  conditions, 
should  have  come  to  believe  that  water  is  the  sole 
food  of  plants ;  nor  that  this  opinion  should  have 
been  held  until  nearly  the  beginning  of  the  eighteenth 
century.  As  a  matter  of  fact,  water  does  contribute 
more  than  half  of  the  materials  which  make  up  the 
dry  matter  of  plants,  and,  as  water,  it  constitutes  from 
three -fourths  to  more  than  nine -tenths  of  their  green 
weight. 

But  while  these  are  the  facts,  and  while  it  is  true 
that  abundant  and  timely  rains  do  make  compara- 
tively poor  soils  produce  large  yields,  it  must  not  be 
inferred  that,  with  ample  and  timely  supplies  of  water 
applied  to  the  soil,  all  else  may  be  neglected  and  the 
hope  entertained  that  any  agricultural  soil  will  thus 
be  held  up  to  a  high  state  of  productiveness  for  an 
indefinite  term  of  years. 

It  is  a  matter  of  universal  experience  that  sewage 
waters,  not  contaminated  with  poisonous  compounds 
and  not  too  highly  concentrated,  cause  lands  to  give 


16  Irrigation    and    Drainage 

much  larger  returns  in  grass  than  do  river,  lake  or 
well  waters.  The  writer  learned,  while  visiting  the 
celebrated  Craigentinny  meadows  near  Edinburgh,  that 
the  purchasers  of  the  grass  from  those  lands  are  very 
particular  to  specify,  as  a  condition  of  their  purchase, 
that  their  grass  shall  be  watered  with  the  day  sewage, 
which  contains  a  higher  per  cent  of  soluble  and  sus- 
pended organic  matter  than  that  of  the  night ;  and 
they  are  also  particular  to  stipulate  that  they  shall 
have  the  first  rather  than  the  second  or  third  use  of 
the  water,  knowing  that  water  which  has  passed  over 
a  cultivated  field  or  meadow  has  lost  something  of  its 
fertilizing  value. 

It  is  asserted,  also,  by  the  owners  and  renters  of 
water  meadows  in  the  south  of  England,  where  the 
irrigation  is  directly  from  the  streams,  that  that  land 
which  receives  the  water  first  is  most  benefited  by  it. 
It  is  true  that  there  are  those  who  contend  that  on  their 
lands  the  second  and  third  waters  are  as  good  as  the 
first,  but  this  is  quite  likely  to  be  due  to  the  presence 
in  those  particular  soils  of  an  abundance  of  the  sub- 
stances carried  by  the  waters. 

It   is,  however,  impossible  to    overestimate  the    im- 
portance of  water  as  a  plant-food.     It  is  indispensable 
and  is  used  more  than  any  other  substance.     It  must 
be  borne  in  mind,  however,  that  irrigation  waters  are 
seldom,  if  ever,  a  complete  plant-food. 

THE    AMOUNT   OF    WATER    USED    BY    PLANTS 

The  amount  of  water  which  is  required  to  mature  crops  of 
various  kinds  under  field  conditions  varies  between  wide  limits  ; 


Amount   of   Water    Used   by   Plants  17 

but  just  what  are  the  precise  factors,  and  what  their  quantitative 
relations,  is  not  yet  so  definitely  known  as  it  needs  to  be.  The 
problem  is  manifestly  a  complex  one,  and  many  of  the  factors 
are  obscure,  and  will  only  be  made  known  in  their  quantitative 
relations  after  much  patient  critical  w^ork  has  been  done  having 
for  its  prime  object  the  solution  of  this  problem. 

It  has  already  been  pointed  out  that  there  appears  to  be 
relatively  less  water  consumed  in  the  production  of  a  pound  of 
dry  matter  under  some  of  the  conditions  which  exist  in  arid 
America  than  is  required  in  the  more  humid  sections  of  this 
country,  and  that  it  appears  probable  that  a  part  of  this  differ- 
ence is  to  be  sought,  possibly,  in  adaptive  functions  in  the  plant 
itself  and  a  part  in  the  differences  of  soil  conditions. 

Under  the  natural  conditions  of  the  field,  it  would  be  expected 
that  very  much  will  depend  upon  the  character  of  the  season  ; 
that  is,  whether  the  season  is  humid  or  dry,  whether  the  tempera- 
tures are  high  or  low,  whether  the  wind  velocities  are  strong  or 
light,  and  whether  the  amount  of  sunshine  is  more  or  less.  Very 
much,  too,  will  depend  upon  the  soil  and  the  character  of  the 
rainfall,  whether  the  soil  is  open  and  the  rains  are  frequent  and 
heavy,  so  that  considerable  amounts  of  water  are  lost  to  the  crop 
by  percolation  and  under-drainage,  or  whether  the  soil  has  a 
retentive  texture,  and  the  rainfall  is  so  proportioned  that  rela- 
tively small  amounts  are  lost,  nearly  all  being  used  in  the  pro- 
duction of  the  crop.  Then,  too,  the  manner  in  which  the  crop  is 
disposed  on  the  field,  whether  it  covers  the  surface  closely,  as  do 
the  grasses  and  small  grains,  or  whether  considerable  areas  of 
the  field  are  exposed  to  the  direct  action  of  wind  and  sun,  as  in 
many  of  the  hoed  crops  and  in  orchards,  must  have  a  marked 
influence  in  determining  the  actual  amount  of  water  which  will 
disappear  or  will  need  to  be  applied  during  a  season,  in  order 
to  maintain  the  best  moisture  conditions  for  the  particular 
crop. 

Then,  again,  the  treatment  of  the  soil  itself  will  have  much 
to  do  with  the  quantity  of  water  which  disappears  at  once  from 
the  surface  without  in  any  way  benefiting  the  crop,  and  also  the 
quantity  which  drops  at  once  entirely  through  the  root  zone,  con- 


18  Irrigation    and    Drainage 

tributing  nothing  to  the  physiological  processes  which  are  involved 
in  the  production  of  the  harvest  sought. 

Irrigation  and  land  drainage  are,  each  of  them,  methods  of 
treatment  of  field  conditions  which  aim  to  modify  and  control  the 
quantitative  relations  of  the  water  which  the  soil  shall  contain, 
and  hence  it  becomes  a  matter  of  importance  to  know  how  much 
water  is  necessarily  involved  in  the  production  of  a  given  amount 
of  a  given  crop.  Much  work  has  been  done  by  various  investi- 
gators bearing  upon  this  problem,  but  in  all  of  those  cases  the 
work  has  been  by  methods  and  appliances  which  have  placed  the 
plants  experimented  with  under  such  conditions  that  the  roots 
were  forced  to  develop  in  a  volume  of  soil  which  was  much  small er 
than  field  conditions  usually  afford.  In  the  writer's  work,  how- 
ever, he  has  aimed  to  give  the  plants  more  nearly  the  normal 
amount  of  root  room  ;  and  in  one  series  has  aimed,  also,  to  so 
place  the  experiment  that  the  plants  should  be  growing  as 
nearly  as  possibly  under  the  meteorological  conditions  of  the  field 
crop. 

.The  apparatus  used  for  this  work  is  illustrated  in  Fig.  1, 
where,  for  the  first  trials,  50 -gallon  vinegar  casks  were  used  for 
pots  in  which  to  place  the  soil.  But  after  the  first  year's  work 
these  were  abandoned,  and  there  were  substituted  for  them,  for 
the  field  work,  galvanized  iron  cylinders  18  inches  in  diameter  and 
42  inches  deep.  These  were  placed  in  pits  in  the  ground  in  the 
field,  as  illustrated  in  Fig.  1,  so  that  the  tops  of  the  cylinders 
were  at  the  level  of  the  top  of  the  field  soil,  and  so  that  the  cylin- 
ders in  which  the  experimental  plants  were  growing  stood  in  the 
field  surrounded  by  the  crop  of  the  same  kind  growing  under  field 
conditions.  The  object  of  placing  the  experiment  in  this  manner 
was  to  secure  for  the  plants,  as  nearly  as  possible,  the  meteorologi- 
cal conditions  of  the  field,  and  these  conditions  were  quite  closely 
realized  in  all  particulars  except  the  one  of  soil  temperature.  In 
this  particular  the  cylinders,  being  necessarily  isolated  from  the 
body  of  the  field  soil  in  order  that  they  might  be  weighed  at  any 
time,  allowed  the  soil  to  take  more  nearly  the  temperature  of  the 
atmosphere  than  was  true  of  the  deeper  layers  of  soil  in  the  field, 
and  also  to  be  subject  to  wider  diurnal  changes  in  the  lower  por- 


Water  Required  for  a  Pound  of  Dry  Matter     19 


Fig.  1.     Method  used  to  measure  "the  amount  of  water  required  to  produce 
a  pound  of  dry  matter. 

tions  of  the  cylinders  than  could  have  occurred  in  the  correspond- 
ing depths  in  the  field  soil.  Just  how  these  differences  of  tem- 
perature conditions  have  modified  the  results  we  are  not  yet  in  a 
position  to  say,  but  it  is  not  likely  that  they  have  caused  very 


20  Irrigation   and    Drainage 

wide  departures  from  what  would  have  been  observed  had  it  been 
possible  to  have  measured  as  accurately  the  water  consumed  by 
the  surrounding  plants  of  the  same  kind  which  were  growing  at 
the  same  time  in  the  field  under  every  way  normal  field  condi- 
tions. 

In  all  of  these  pot  experiments,  the  effort  has  been  to  hold 
the  amount  of  moisture  in  the  soil  at  a  constant  quantity  equal 
to  that  which  was  possessed  by  the  field  soil  in  the  spring  of 
the  year,  when  it  was  in  good  working  condition  ;  and  this 
was  done  by  weighing  the  cylinders  periodically,  usually  as 
often  as  once  a  week,  and  then  adding  water  in  sufficient  quan- 
tity to  bring  the  weight  of  the  cylinder  back  to  the  original 
amount.  The  cylinders  were,  of  course,  water-tight,  so  that  the 
only  loss  was  through  evaporation  from  the  surface  of  the  soil  in 
the  cylinders  and  from  the  plants  themselves.  No  effort  has  been 
made  in  these  experiments  to  distinguish  between  the  amount  of 
water  which  actually  passed  through  the  plant  and  was  evaporated 
from  its  surface,  and  that  which  escaped  from  the  surface  of  the 
soil  in  which  the  plants  were  growing,  as  to  do  this  would 
necessitate  the  covering  of  the  soil  in  which  the  plants  were  grow- 
ing so  as  to  prevent  evaporation  from  it.  To  do  this  effectively 
would  interfere  with  the  normal  aeration  of  the  soil,  and  thus  viti- 
ate the  results  by  producing  abnormal  conditions.  During  the 
work  of  the  first  year,  when  the  wooden  casks  were  used,  there 
was  probably  some  loss  of  water  through  the  walls  of  the  casks, 
due  to  capillarity  in  the  wood  and  evaporation  from  it  ;  but 
the  amount  was  probably  small,  because  they  were  all  well 
painted. 

The  first  year's  trials  were  with  oats,  barley  and  corn.  With 
the  oats  and  barley  the  surface  of  the  soil  was  not  disturbed  after 
seeding,  but  in  the  case  of  the  corn  the  ground  was  stirred  after 
each  watering,  so  as  to  develop  a  soil  mulch  after  the  manner 
of  field  culture.  In  each  case  the  work  was  done  in  dupli- 
cate. In  the  table  which  follows  are  given  the  results  of  these 
trials  : 


Water    Used    by    Plants  21 


*Table  showing  the  amount  of  water  evaporated  from  plant  and  soil  in  producing 
«  pound  of  dry  matter  in  Wisconsin  in  1891 

Dry  matter    Water  per  Ib.  of    Water  as  inches 
Water  used      produced  dry  matter  of  rain 

l-BS.  LBS.  LiBS.                               INCHES 

Barley  1 158.3  .3966  399  14 ) 

Barley  2 141.03  .3488  404.33  / 

Oats  1 224.25  .4405  509.311 

Oats  2 220.7  .4471  493  63  ) 

Corn  1 '  300.45  1.0152  295.95) 

Corn  2 298.65  .9727  307.03  / 


It  will  be  seen  from  an  inspection  of  the  table  that  the  sev- 
eral experiments  agree  among  themselves  as  closely  as  could  be 
expected,  and  that  the  barley  used  13.19  inches  of  water  in 
coming  to  maturity,  the  oats  19.6  inches,  and  the  corn  26.39 
inches. 

During  the  same  season  an  effort  was  made  to  measure  the 
water  required  for  a  crop  of  corn  under  perfectly  normal  field 
conditions.  To  do  this  two  plots  of  ground,  each  48  feet  long 
and  42  feet  wide,  were  planted  to  a  local  form  of  Pride  of  the 
North  dent  corn,  in  rows  3.5  feet  apart  and  in  hills  16  inches 
apart  in  the  rows,  the  corn  being  thinned  to  two  stalks  in  a  hill 
after  it  had  come  up  and  was  well  established.  At  the  time  of 
planting,  samples  of  soil  were  taken  in  1-foot  sections  to  a  depth 
of  4  feet  from  six  different  places  on  each  plot,  and  the  water 
in  the  soil  determined.  This  was  also  done  when  the  corn  was 
cut,  in  order  to  get  a  measure  tof  the  change  in  the  water  con- 
tent of  the  soil,  which  it  was  proposed  to  add  to  the  measured 
rainfall  of  the  growing  season,  to  give  the  amount  of  water 
used. 

At  the  time  of  maturity,  the  whole  of  the  corn  of  each  plot 
was  cut  and  dried  in  a  large  dry-house,  in  order  to  get  an  exact 
measure  of  the  amount  of  dry  matter  produced.  There  is  given 
below  the  water  content  of  the  soil  in  the  two  plots  at  the  time 
of  planting  and  at  the  time  of  harvest : 


*Eighth  Annual  Report  Wisconsin  Experiment  Station,  p.  126. 


22 


Irrigation   and    Drainage 


*Table  showing  the  changes  in  the  water  content  of  the  soil  upon  which  corn  had 
been  grown,  in  1890  under  field  conditions 


Dry  weight  of  soil  per 
cubic  foot 


First  foot 
77.25  Ibs. 


PEROT.  LBS. 

f  June  7  ........  22.66  17.5 

PLOTI    |  Sept.  16  .......  15.75  12.17 

[  Loss  ..........  6.91  5.33 

[June  7  ........  24.93  19.26 

PLOT  II  \  Sept.  16  .......  18.43  14.24 


Loss  ..........  6-5 


5.02 


Second  foot 
79.79  Ibs. 

Third  foot 
94.13  Ibs. 

Fourth  foot 
98.07  Ibs 

PER  CT.  LBS. 

PEROT.  LBS. 

PER  CT.  LBS. 

19.77    15.77 

18.16    17.09 

19.16    18.7!) 

11.8        9.42 

9.91      9.33 

10.77     1#.56 

7.97      6.35 

8.25      7.76 

8.39      8.2:! 

24.32    19.4 

20.08    18.9 

19.37     1!) 

15.03    11.99 

12.62    11.88 

9.8        9.61 

9.29      7.41 

7.46      7.02 

9.57      9.39 

From  this  table  it  appears  that  each  volume  of  soil  four  feet 
long  and  one  square  foot    in  section  lost  the  amounts  of  water 

which  follow: 

Plot  I 

LBS. 

Loss  of  water  in  soil 27.67 

Rainfall  from  June  7  to  Sept.  16 64.72 


Plot  II 

LBS. 

28.84 
64.72 


Total  loss . .  92.39 


93.56 


17.76  inches    17.99  inches 

The  amount  of  dry  matter  produced  in  these  cases  was,  for 
Plot  I,  450.18  pounds;  Plot  II,  455.36  pounds,  making  a  yield  per 
acre  of  9,727  pounds  and  9,840  pounds  for  the  two  plots  respectively. 

Were  it  admissible  to  assume  that  the  percolation  of  rain- 
water bslow  the  zone  of  root  action  had  been  exactly  equaled  by 
the  rise  of  water  into  it  by  capillarity  from  the  subsoil  below,  it 
would  follow,  from  the  observed  losses  of  water  and  yields  of  dry 
matter,  that  the  amount  of  water  used  for  a  pound  of  dry  matter 
under  these  field  conditions  was  413.7  pounds  for  Plot  I,  and  414.2 
pounds  for  Plot  II. 

The  results  of  a  trial  similar  to  the  one  just  described,  and  with 
the  same  variety  of  corn,  for  the  year  1891,  gave  309  pounds  of 
water  for  one  pound  of  dry  matter,  on  ground  which  had  been  given 
a  dressing  of  farmyard  manure,  and  333  pounds  of  water  for  u 
pound  of  dry  matter  on  land  which  had  not  been  manured.  Here 
we  have  two  trials  by  pot  culture,  where  everything  was  under 


*Eighth  Annual  Report  Wisconsin  Experiment  Station,  p.  123, 


Water    Used   ly   Plants  23 

control,  and  there  could  be  no  percolation,  which  gave  an  aver- 
age of  301.49  pounds  of  water  for  a  pound  of  dry  matter.  We  also 
have  four  field  trials,  where  there  is  the  uncertainty  of  some  loss 
of  water  by  percolation  and  of  some  gain  by  capillarity  from 
below,  which  gave  a  mean  of  413.95  pounds  for  1890,  and  in  1891 
321  pounds  of  water  for  a  pound  of  dry  matter.  The  amount  of 
percolation  during  the  season  of  1890  was  certainly  greater  than  it 
was  during  the  season  of  1891,  and  this  may  or  may  not  be  an 
explanation  of  the  difference  in  the  amounts  of  water  used  per 
pound  of  dry  matter  in  the  two  seasons. 

In  the  case  of  oats  grown  under  field  conditions  and  studied 
in  the  same  manner  as  that  described  for  the  corn,  the  results 
showed  519  pounds  of  water  for  a  pound  of  dry  matter  in  the  one 
case,  and  534  pounds  in  another  case,  while  the  average  of  the 
two  pot  experiments  was  501.47  pounds  of  water  for  one  pound 
of  dry  matter. 

So,  too,  in  the  case  of  field  studies  with  barley,  we  had  an 
observed  loss  of  537  pounds  of  water  in  one  case  on  ground  which 
had  been  fallow,  but  719  pounds  on  ground  which  had  not  been 
fallow,  for  each  pound  of  dry  matter  produced  ;  while  the  pot 
culture  gave  a  mean  loss  of  only  401.74  pounds  of  water  for  a 
pound  of  dry  matter. 

If  we  count  the  rainfall  during  the  growing  season  and  the 
difference  between  the  amounts  of  water  in  the  soil  at  the  time 
of  planting  and  at  harvest,  in  the  several  field  cases,  as  the 
amounts  of  water  used  by  the  crop,  including  surface  evaporation, 
and  then  compare  these  amounts  per  square  foot  with  those  added 
to  the  several  pots  in  the  pot  trials,  we  shall  have  results  which 
are  given  below: 

Table  showing  number  of  pounds  of  water  consumed  per  square  foot 

, Oats . 

In  pots  In  field    Difference 

Mean  amount  of  water  per  sq.  ft.-lbs 101.98  72.98  29 

Mean  amount  of  water  per  sq.  ft.-lbs 79.11  58.65  20.46 

Mean  amount  of  water  per  sq.  ft.— Ibs 137.3  63.8  73.5 


24 


Irrigation   and    Drainage 


From  these  figures  it  appears  that  while  more  water  was  lost 
in  the  field,  for  each  pound  of  dry  matter  produced,  than  in  the 
pot  experiments,  the  amount  of  water  used  per  square  foot  in 
the  pots  was  in  every  case  much  greater  than  it  was  in  the  field. 
So,  too,  were  the  yields  of  dry  matter,  when  expressed  in 
units  of  equal  areas,  much  greater  in  the  pots  than  they  were  in 
the  field.  These  relations  are  very  suggestive,  though,  of  course, 
not  at  all  demonstrative,  that  the  larger  amount  of  water  used 
per  unit  area  in  the  pot  experiments  is  to  be  credited  with  the 
larger  amount  of  dry  matter  produced  per  unit  area.  The  differ- 
ences are  certainly  in  the  direction  we  should  expect  if  water 
plays  the  important  part  we  have  attributed  to  it,  and  if  in  the 
field  experiments  the  several  crops  did  not  have  all  of  the  water 
they  might  have  used  to  advantage. 

In  1892  pot  experiments  similar  to  those  described  were  con- 
ducted with  barley,  oats,  corn,  clover,  and  field  peas,  using  gal- 
vanized iron  cylinders  18  inches  in  diameter  and  42  inches  deep, 
placed  in  the  field,  surrounded  by  the  field  crop,  and  each  experi- 
ment being  in  duplicate.  The  results  of  these  trials  are  given  in 
the  table  below: 

Table  showing  the  amount  of  water  used  in  producing  a  pound  of  dry  matter 
in  Wisconsin  in  1892 

Dry  matter    Water  per  Ib.  of    Computed  yield    Water 
produced  dry  matter  per  acre  used 


Water  used 

LBS. 

Barley  1... 

...    216.12 

Barley  2.  .  . 

...    206.12 

Oats      1... 

...    174.6 

Oats      2... 

...    167.58 

Corn     1... 

...    235.96 

Corn     2... 

...    225.24 

Clover  1.... 

...    337.36 

Clover  2  

..    34866 

Peas      1... 

...    155.24 

Peas      2..., 

...    139.17 

LBS. 
.576 

.3322 

.9905 
.5657 
.5977 

.3252 


LBS. 
375.21 

525.59 

238.22 
398.15 
564.43 

477.37 


14,196 
8,189 
19,184 
12,486 
8,017 


23.52 
19 
25 
29.73 


If,  now,  we  express  the  relation  between  the  amount  of  dry 
matter  produced  and  the  number  of  inches  of  water  used  in  these 
trials  and  in  those  of  1891,  it  will  be  seen  that  the  yields  of  dry 


Water    Used   by    Plants  25 

matter  per  acre  are  measurably  proportional  to  the  amount  of 
water  used  by  the  crop  in  producing  it.  These  relations  are 
expressed  in  the  following  table: 


• In  the  field « In  cylinders 

Dry  matter    Water  used    Dry  matter    Water  used 

LBS.  PKB  ACRE   INCHES  LBS.  PER  ACRE   INCHES 

Oats  in  1891 6,083                   13.93                 8,861  19.69 

Oats  in  1892 8,189  19 

Barley  in  1891 4,157                  11.27                7,441  13.19 

Barley  in  1892 14,196  23.52 

Corn  in  1891 8,190.5               12.26               19,845  26.39 

Corn  in  1892 7,045.3               11.34               19,184  25.09 

Clover  in  1892 12,496  29.73 

Peas  in  1892 8,017  16.89 


Now,  here,  in  the  case  of  the  oats,  the  average  yield  of  dry 
matter  per  acre  in  the  cylinders  was  4.26  tons,  while  in  the  field 
it  was  3.04  tons.  But  the  soil  put  into  the  cylinders  in  the  spring 
was  the  same  as  that  in  the  field  and  contained  the  same  per  cent 
of  soil  moisture,  but  there  was  given  to  the  soil  in  the  cylinders 
1.39  times  the  amount  of  water  which  fell  as  rain  upon  the  sur- 
rounding fields,  plus  the  amount  of  water  by  which  the  soil  was 
dryer  at  harvest  than  at  seed-time  ;  and  we  had  a  yield  1.4  times 
as  large. 

In  the  experiment  with  barley,  we  had  an  average  yield  of 
5.41  tons  of  dry  matter  per  acre  in  the  cylinders,  but  only  2.08 
tons  in  the  field.  There  were  added  to  the  cylinders  1.63  times 
the  amount  of  water  which  fell  upon  the  field,  plus  the  amount 
of  water  by  which  the  soil  was  dryer  at  harvest  than  at  seed-time, 
and  we  realized  a  yield  of  dry  matter  2.6  times  as  large.  There 
was  in  the  field  a  yield  of  40  bushels  of  grain  per  acre,  but  in 
the  cylinders  104  bushels,  and  yet  so  far  as  we  can  see,  the  only 
advantage  the  barley  in  the  cylinders  had  over  that  in  the  field 
was  the  increased  amount  of  water  added  to  the  soil. 

In  the  case  of  corn,  the  yield  of  dry  matter  per  acre  in  the 
cylinders  was  nearly  2.6  times  as  large  as  that  in  the  field,  and 
there  was  added  to  the  soil  in  which  this  corn  grew  a  little  less 


26  Irrigation   and    Drainage 

than  2.2  times  the  amount  of  water  which  was  available  for  the 
field  crop. 

In  1893,  oats  used  water  at  the  rate  of  595  pounds  per  pound  of 
dry  matter  on  a  sandy  soil  where  the  yield  was  1.196  pounds  on 
7.069  sq.  ft.,  making  a  yield  of  7,370  pounds  of  dry  matter  per  acre. 
But  in  this  case  the  pot  was  a  galvanized  iron  cylinder  6  feet  deep, 
standing  above  the  ground,  so  that  the  evaporation  would  neces- 
sarily be  large,  as  the  figures  show  it  was.  Expressed  in  inches, 
the  water  used  was  equal  to  19.37  inches  of  rain. 

Clover,  too,  was  grown  in  the  usual  form  of  cylinder  in  the 
ground  in  the  field,  and  two  crops  cut  from  each  of  two  cylinders, 
producing  the  yield  and  using  the  amounts  of  water  stated  below: 

/ — First  crop — >  /— Second  cvop—> 

No.  1        No.  2  No.  1        No.  2 
LBS.           LBS.  LBS.  LBS. 

Dry  matter  per  acre 7,000          9,353  5,734        7,886 

Water  per  pound  of  dry  matter 423.14        370.92  983.7        730.9 

It  will  be  seen  that  in  these  cases  the  first  crops,  which  were 
cut  July  1,  were  much  more  economical  of  water  used  than  were 
the  second  crops,  when  measured  by  the  standard  of  the  number 
of  pounds  of  water  per  pound  of  dry  matter  produced.  Express- 
ing the  water  used  in  inches  over  the  surface  covered  by  the 

crop,  the  results  stand  : 

— First  crop —  >— Second  crop— ^ 

No.  1       No.  2  No.  1       No.  2 

INCHES     INCHES  INCHES    1NCHKS 

Inches  of  water  used 13.06        15.28  24.89        25.44 

It  is  thus  seen  that  the  two  crops  of  clover,  averaging  for 
the  four  cases  a  yield  of  7.493  tons  of  dry  matter  per  acre,  and 
equivalent  to  8.815  tons  of  hay  containing  15  per  cent  of  water, 
used  for  the  season  a  mean  of  39.33  inches  of  water,  an  amount 
which  considerably  exceeds  the  total  annual  rainfall  of  the  year 
for  this  locality. 

Side  by  side  with  the  clover  trials  of  1893,  four  cylinders  were 
treated  in  the  same  manner  for  corn,  all  of  them  growing  a  flint 
variety.  In  these  cases,  too,  one  cylinder  of  each  pair  had  its 


Water    Used   by   Plants  27 

soil  enriched  with  farmyard  manure,  to  determine  if  a  rich  soil 
affected  in  any  notable  way  the  rate  at  which  water  was  used  in 
crop  production. 

The  results  of  these  trials  may  be  stated  as  given  below: 

— Flint  corn < Flint  corn 

Manured      Not  man'd      Manured      Not  man'd 

1234 
LBS.  LBS.  LBS.  LBS. 

Dry  matter  per  acre 34,730  33,620  22,540  9,505 

Water  used  per  Ib.  of  dry  matter        223.3  232  257.4  223 

Water  expressed  in  inches 34.23  34.42  25.56  13.06 


The  difference  in  yield  between  cylinders  3  and  4  and  1  and  2 
appears  to  have  been  due  to  the  condition  of  the  soil  at  the  time 
the  cylinders  were  fitted,  the  soil  being  more  moist  in  3  and  4, 
which  stood  upon  ground  lower  and  too  wet  for  conditions  of  best 
growth.  The  field  yield  of  corn  surrounding  the  cylinders,  and 
with  the  same  kind  of  soil,  was  4.4  tons  of  dry  matter,  yielding 
66.95  bushels  of  kiln-dried  shelled  corn  per  acre,  which  is  large 
for  field  conditions  with  the  normal  rainfall.  But  the  mean  yield 
in  cylinders  1  and  2  was  17.09  tons  of  dry  matter  per  acre,  or 
almost  four  times  as  much,  while  the  average  of  the  four  cylinders 
was  2.85  times  as  large,  but  using  2.2  times  the  amount  of  water 
which  fell  upon  the  surrounding  fields  as  rain  during  the  growing 
season  for  this  corn. 

It  does  not,  of  course,  follow  from  these  experiments  that  well 
tilled  field  soil,  if  irrigated  properly,  will  produce  such  yields  as 
these  which  have  been  recorded  ;  neither  does  it  follow,  neces- 
sarily, that  these  large  yields  owe  their  excess  over  normal  crops 
only  to  the  extra  supply  of  water  added  at  the  proper  times. 
It  does,,  however,  follow  from  these  experiments,  we  think,  that 
were  our  water  supply  under  better  control  and  larger  at  certain 
times  than  it  is  in  Wisconsin,  our  field  yields  would  be  much 
increased,  if  not  actually  doubled.  It  does  follow,  also,  from 
these  experiments,  that  well  drained  lands  in  Wisconsin  and  in 
other  countries  having  similar  climatic  conditions  are  not  supplied 
naturally  with  as  much  water  during  the  growing  season  as  most 


28 


Irrigation   and    Drainage 


crops  are  capable  of  utilizing,  and,  hence,  that  all  methods  of  till- 
age which  are  wasteful  of  soil  moisture  detract  by  so  much  from 
the  yields  per  acre.  Indeed,  what  we  call  good  average  yields 
per  acre  are  determined,  in  a  large  measure,  by  the  amount  of 
soil  moisture  which  the  land  is  capable  of  turning  over  to  the 
crops  growing  upon  it. 

In  1894,  work  similar  to  that  described  was  done  with  pota- 
toes, eight  cylinders  being  used,  two  of  which  were  placed  in  the 


Fig.  2.    Potatoes  grown  in  cylinders  to  determine  the  amount  of  water 
used  in  producing  a  crop. 

field,  as  already  described,  and  six  others  were  kept  standing  upon 
the  surface  of  the  ground,  shaded  on  the  south  side  from  the  sun 
in  the  manner  represented  in  Fig.  2,  which  shows  the  potatoes  as 
they  appeared  when  growing.  In  the  same  year,  oats  were  again 
grown  in  four  other  cylinders  surrounded  by  field  grain  of  the 
same  kind,  and  in  pots  with  their  tops  flush  with  the  top  of  the 
ground.  A  statement  of  the  results  of  these  several  trials  is 
here  given. 

We  give,  in  the  first  place,  in  illustration  of  the  rate  at  which 
potato  plants  use  water  in  the  various  stages  of  their  growth,  a 


Water    Used   by   Plants 


29 


table  showing  the  times  of  watering  and  the  amounts  of  water 
given  through  the  whole  growing  season  for  the  crop  : 

Table  showing  the  times  of  watering  potatoes,  and  the  amounts  of 

water  given 
• — In  field — «  i Cylinders  above  ground 


No.  1 

No.  2 

No.  1 

No.  2 

No.  3 

No.  4 

No.  5 

No.  6 

LBS. 

LBS. 

LBS. 

LBS. 

LBS. 

LBS. 

LBS. 

LBS. 

Weights  at  start  

504 

506.7 

581 

576.5 

579.6 

579.7 

582 

579.5 

May  15,  water  added  .  . 

19.8 

18.4 

18.2 

17.8 

17.9 

18.3 

June  4, 

10 

10 

June  13,     ' 

10 

10 

10 

10 

10 

10 

10 

10 

June  21,     "           "     .. 

18 

is 

10 

10 

10 

10 

10 

10 

June  25 

10 

10 

June  30,     "           " 

10 

10 

July  2,        "           "     .. 

10 

10 

10 

10 

10 

10 

10 

10 

JulyS,        "           "     .. 

15 

15 

10 

10 

10 

10 

10 

10 

July  9,        "           "     .. 

20 

20 

10 

10 

10 

10 

10 

10 

July  12,      "           "     .. 

20 

20 

12 

12 

12 

12 

12 

12 

July  16,      "           "     .. 

15 

15 

10 

10 

10 

10 

10 

10 

July  20,      "            "     .. 

15 

15 

15 

15 

15 

15 

15 

15 

July  24,      "           "     .. 

10 

10 

8.9 

7.1 

5.2 

10.6 

12 

6 

July  28.      "           "     .. 

15 

15 

15 

15 

15 

15 

15 

15 

Aug.  2.       "            "     .. 

10 

10 

10 

10 

10 

10 

10 

10 

Aug.  10,     '              '     .. 

15 

20 

9.8 

22.7 

18 

18.3 

15.1 

21.7 

Aug.  16,     "           "     .. 



10 

10 

10 

10 

10- 

10 

Aug.  25,      '             "     .. 



8.1 

21.4 

20.9 

16.9 

10.3 

22.1 

Weights  at  close  

481.7 

492 

554 

527.8 

531.6 

528.8 

545.5 

521.4 

Total  water  added  

198 

203 

168.6 

191.6 

184.3 

185.6 

177.9 

190.1 

Soil  water  used  

22.3 

14.7 

27 

48.7 

48 

50.9 

36.5 

58.1 

Dry  matter 

.5 

.5 

.3 

.5 

.5 

.5 

.4 

.5 

Total  water 

220.8 

218.2 

195.9 

240.8 

232.8 

237 

214.8 

248.7 

Water  used,  in  inches. 

24.02 

23.74 

21.31 

26.2 

25.33 

25.78 

23  27 

27.06 

The  potatoes  in  the  two  field  cylinders  matured  first,  and  were 
dug  on  Aug.  25,  while  the  others  stood  until  Sept.  21.  It  should 
be  stated  in  this  connection  that  all  of  the  potatoes,  including 
those  in  the  field,  were  affected  by  the  hot  weather  blight,  so  that 
in  no  case  were  the  plants  in  full  vigor  and  presenting  the  normal 
amount  of  foliage  to  the  atmosphere. 

The  yields  of  tubers  in  the  several  cases,  and  the  computed 
vields  per  acre,  figured  as  proportional  to  the  surface  and  vol- 


30  Irrigation   and    Drainage 

ume  of   soil  in  which    the  crop  grew,  are  given  in  the  table  be- 
low: 

CYLINDERS  IN  THE  GROUND 

— Weight  of  tubers —  — Yield  per  acre 

Merchantable  Merchantable 

tubers        Small        Total  tubers        Small        Total 

LBS.  LBS.  LBS.  BU.  BU.  BIT. 

No.  1 ...     1.308  .386  1.694  537.3  158.5         695.8 

No.  2 817  .775  1 .593  335.6  318.3          653.9 

CYLINDERS  ABOVE  GROUND 

No.  1 452  .539  Ml  185.6  221.5  407.1 

No.  2 379  .792  1.171  155.7  325.5  481.2 

No.  3 322  .875  •      1.197  M2.4  359.2  491.6 

No.  4 1.024  .314  1.338  420.6  128.9  549.5 

No.  5 709  .282  1.091  291.2  156.9  448.1 

No.  6 681  .435  1.116  279.9  178.8  458.7 

It  will  be  seen  from  the  relation  between  the  weights  of  small 
and  merchantable  tubers  that  the  blight  referred  to  had  exerted  a 
very  appreciable  influence  on  the  crop  in  all  of  the  cases,  so  that 
the  relations  which  exist  between  the  water  used  and  the  dry 
matter  produced  cannot  be  regarded  as  normal.  These  relations, 
as  they  were  found  to  stand,  are  given  below: 

Table   showing   the  pounds  of   water  used   by  potatoes  in  producing   a  pound 
of  dry  matter  in  tuber  and  vine  in  Wisconsin  during  the  season  of  1894 


Water  per  Ib.  of 

Computed  yield  of 

Dry  matter 

dry  matter 

dry  matter  per  acre 

Water  used 

LBS. 

LBS. 

LBS. 

INCHES 

No.  1  

.513 

430.4 

12,650 

24.02 

No.2  

.5258 

415 

12,960 

23.74 

No.  1  ... 

.3338 

5869 

8,248 

21.31 

No.  2  

.5007 

480.9 

12,340 

26.2 

No.  3...... 

.4505 

516.8 

11,110 

25.33 

No.  4  

.5020 

472.1 

12,370 

25.78 

No.  5  

.3596 

497.3 

8,865 

23.37 

No.  6. 

5425 

458.4 

13.370 

270fi 

It    is    evident    from   this    table,   whatever   may   be   said    in 
regard  to  the  yields,  that  the  potatoes  did  use  a  very  large  amount 


Water    Used   by    Plants  31 

of  water,  although  it  was  unquestionably  less  than  it  would  have 
been  had  the  plants  not  been  affected  by  the  blight.  As  it  was, 
the  plants  received  an  average  of  24.6  inches,  which  is  three  times 
the  amount  of  rainfall  during  their  season  of  growth. 

It  should  be  said  further,  in  regard  to  the  amount  of  water 
used  this  season,  that  the  whole  of  the  watering  was  from  the 
bottom,  so  that  the  surface  of  the  ground  was  kept  dry  throughout 
the  time.  In  order  to  introduce  the  water  at  the  bottom,  a  layer 
of  sand  was  first  placed  in  each  cylinder  before  the  soil  was  filled 
in,  and,  then  a  column  of  3 -inch  drain  tile  was  set  up  against  one 
side,  reaching  from  the  bottom  to  the  top  of  the  cylinders,  and  in 
adding  the  water  it  was  poured  into  these  tiles. 

In  the  case  of  the  cylinders  of  oats  which  were  grown  in  1894, 
they  were  watered  in  the  same  manner,  so  that  in  these  cases 
nearly  all  of  the  water  used  did  actually  pass  through  the  plants. 

The  results  with  the  oats  are  given  below: 

No.  1  No.  2  No.  3  No.  4 

LBS.  LBS.  LBS.  LiBS. 

Amount  of  water  used 282.8  280.2              283.3             285.6 

"   dry  matter  produced..              .5232  .5165               .4198              .4663 
"   water   per  Ib.  of    dry 

matter 540.6  542.7               674.9             614.7 

Vl        "   dry  matter  per  acre ...  12,900  12,730            10,350            11,500 

IN.  IN.  IN.  IN. 

Total  water  used,  in  inches 30.77  30.48  30.82  31.18 

If  reference  is  made  to  the  yields  of  1891  and  1892,  which  have 
been  given  on  a  preceding  page,  it  will  be  seen  that  the  yields  for 
1894  have  been  decidedly  larger  than  they  were  in  the  former 
cases,  but  so  were  the  amounts  of  water  used  by  the  plants.  The 
mean  of  the  three  earlier  trials  gives  a  yield  of  8,525  pounds  of  dry 
matter  per  acre,  using  19.345  inches  of  water  to  produce  it;  but 
in  these  last  cases  the  mean  yield  of  dry  matter  was  11,870  pounds 
per  acre,  and  the  water  used  to  produce  it  was  31.08  inches.  The 
yields  of  1894  average  1.39  times  the  earlier  ones,  and  the  amount 
of  water  used  in  producing  this  greater  yield  was  1.06  times  the 
amount  required  for  the  smaller. 


32  Irrigation    and    Drainage 

In  1895,  and  again  in  1896,  similar  experiments  were  carried 
on  with  potatoes,  barley  and  clover,  both  upon  very  sandy  soils 
and  upon  good  clay  loam.  The  first  experiments  described  were 
with  potatoes  on  very  sandy  soil  taken  from  the  pine  barrens  in 
Douglas  county,  Wis.,  and  which  was  auite  coarse-grained  and 
deficient  in  organic  matter. 

On  June  3,  1895,  the  three  cylinders  in  the  right  of  the  pho- 
tograph, Fig.  2,  were  filled  with  the  soil  in  question.  Some  2,000 
pounds  of  this  soil  had  been  procured  from  the  surface  down  to  a 
depth  of  three  feet.  The  first,  second  and  third  feet  of  the  soil 
were  placed  in  them  in  their  natural  order  in  the  field,  the  third 
foot  being  at  the  bottom  and  the  surface  foot  at  the  top,  so  as 
to  reproduce  the  natural  conditions  as  closely  as  possible. 

In  cylinder  1,  on  the  right,  the  soil  was  left  in  its  virgin  con- 
dition ;  to  No.  2  there  was  applied  two  pounds  of  well -rotted 
farmyard  manure,  and  to  No.  3  there  were  given  four  pounds. 
The  remaining  three  cylinders,  4,  5  and  6,  were  used  as  checks, 
and  were  filled  to  within  5  inches  of  the  top  with  good  surface 
soil  of  a  light  clay  loam  character.  In  order  that  the  tubers  of 
the  potatoes  might  develop  under  as  closely  similar  conditions  as 
possible,  and  that  the  surface  evaporation  from  the  soil  might  not 
be  very  different,  there  was  placed  upon  the  surface  of  cylinder 
4  five  inches  of  the  surface  soil  from  the  pine  barrens,  on  cylin- 
der 5  five  inches  of  the  second  foot,  and  upon  6  five  inches  of  the 
third  foot. 

In  planting,  one  tuber  of  the  Alexander  Prolific  potato  was 
cut  in  halves  and  the  two  pieces  planted,  so  as  to  give  two  hills  in 
each  cylinder.  The  cylinders  were  weighed  and  watered  once 
each  week,  water  enough  being  given  to  maintain  a  constant 
weight. 

In  1896,  the  cylinders  were  again  planted  in  the  same  manner 
with  Rural  New-Yorker  potatoes.  No  fertilizers  were  used,  but  the 
plants  were  watered  twice  each  week,  5  pounds  of  water  being 
given  to  each  cylinder  every  Monday  morning  and  enough  more 
on  every  Thursday,  when  the  cylinders  were  weighed,  to  bring 
them  to  a  constant  weight.  This  change  was  made  because  it 
appeared  possible  that  the  texture  of  the  soil  was  too  coarse  to 


Water    Used   by    Plants 


33 


permit  a  single  watering  every  seven  days  to  meet  the  needs  of 
the  plants. 

The  results  of  the  two  years  are  given  in  the  following  table: 

1234  56 

BU.  BU.  BU.  BU.  BU.  BU. 

Yield  per  acre,  1896 5135        862.6        801  1,089  1,119  883.2 

'     1895 74  450  284  279  416  152 

Difference 449.5        412.6        517  810  703  731.2 

IN.  IN.  IN.  IN.  IN.  IN. 

inches  of  water  used,  1896  . .     25.85       27.91        29.07  34.08          32.63       27.51 

'      1895..     10.76        2002        17.65  1627  20.65        12.96 

Difference 15.09          7.89        11.42  17.81  11.98        14.55 


It  will  be  seen  from  this  table  that  both  the  yield  of  potatoes 
and  the  amount  of  water  used  are  much  larger  in  1896  than  they 
are  in  1895,  the  average  yield  in  1896  being  878.1  and  in  1895 
only  275.8  bushels,  the  former  being  3.18  times  the  latter.  The 
average  amount  of  water  used  was  29.51  inches  in  1896,  and  16.385 
inches  in  1895,  the  former  being  1.8  times  the  latter. 

As  a  further  check  upon  these  experiments,  two  cylinders  7 
feet  deep  and  4.33  feet  in  diameter  were  filled  with  a  local  yellow 
sand,  and  to  one  of  the  cylinders  farmyard  manure  was  applied 
at  the  rate  of  50  tons  per  acre,  and  to  the  other  at  the  rate  of  25 
tons  per  acre.  These  were  planted  in  1895  with  Alexander  Pro- 
lific potatoes,  seven  pieces  in  each  cylinder.  The  watering  in 
1895  was  once  each  week,  and  twice  each  week  in  1896.  In  the 
latter  year  no  fertilizers  of  any  kind  were  applied,  and  Rural 
New-Yorker  potatoes  were  planted  instead  of  the  Alexander  Pro- 
lific. In  1895,  20.05  inches  of  water  gave  a  yield  of  605.5  bushels 
on  the  heavily  manured  cylinder  and  563.5  bushels  per  acre  on 
the  other.  But  in  1896,  when  the  potatoes  were  watered  twice 
each  week  at  the  rate  of  75  pounds  for  the  lightly  manured  case 
and  50  pounds  for  the  other,  the  yield  per  acre  on  the  lightly 
manured  cylinder  was  only  312  bushels,  and  yet  40.61  inches  of 
water  were  used;  while  the  other  cylinder  gave  a  yield  of  344.5 
bushels  per  acre  and  used  31.92  inches  of  water. 


34 


Irrigation   and    Drainage 


In  this  case  it  will  be  seen  that  a  decidedly  smaller  yield  is 
associated  with  a  much  larger  amount  of  water  applied  at  shorter 
intervals,  but  why  this  should  be  does  not  appear,  unless  the 
manure  had  become  exhausted  and  the  plants  were  not  properly 
fed.  The  vines  in  all  cases  were  abnormally  small,  and  looked 
starved. 

In  the  experiments  with  both  barley  and  clover,  the  small 
cylinders  were  used  set  into  the  ground  in  the  field.  Two  cylin- 
ders were  used  for  the  barley  and  four  for  the  clover,  one -half  of 
them  filled  with  the  yellowish  sand  referred  to,  well  manured, 
and  the  other  filled  with  good  soil.  All  the  cylinders  were 
weighed  and  watered  once  each  week,  holding  them  at  a  constant 
weight,  and  the  results  are  given  in  the  table  below: 

Barley,  1895 
Sand        Soil 

Yield  of  dry  matter  in  tons  per  acre 5.02         6-32 

Bushels  of  grain  per  acre S0.47        38.14 

Inches  of  water...  25.84        G1.24 


Tons  dry  matter  per  acre,  No.  1 . .     2.88 


Tons  dry  matter  per  acre,  No.  1. .     1.86 

"       "          "        "      "     N 
Mean  for  two  years  . . 


First 
Sand 

crop 
Soil 

Second  crop 
Sand        Soil 

Both  crops 
Sand         Soil 
Water  used 

INCHES 

2.88 

3.48 

2.36         3.28 

29.36         38.18 

2.91 

3.25 

3.19         2.77 

37.15         39.91 

1.86 

2.45 

4.32         3.63 

22.09         19.78 

2.09 

2.9 

3.62         3.29 

20.87         20  48 

2.435 

3.02 

3.372       3.242 

27.37         29.59 

The  mean  annual  yield  of  clover  on  the  sand  for  the  two  years 
vvas  5.807  tons  of  dry  matter  per  acre,  using  27.37  inches  of 
water,  and  the  mean  product  for  both  crops  on  the  good  soil  for 
the  two  years  was  6.262  tons  of  dry  matter  per  acre,  using  an 
average  of  29.59  inches  of  water  to  produce  it. 

In  addition  to  the  field  results  which  have  now  been  presented, 
measuring  the  water  used  in  the  production  of  crops  in  Wisconsin; 
we  have  obtained  some  results  in  essentially  the  same  manner, 
except  that  the  cylinders  were  made  deep  enough  to  contain  four 


Water    Used   by    Plants 


35 


feet  of  soil,  and  all  were  placed  in  the  plant-house,  arranged  in 
the  manner  shbwn  in  Fig.  3. 

In  these  trials,  two  sizes  of  cylinders  have  been  used  :  one  18 
inches  in  diameter  and  51   inches  deep,  and  the  other  36  inches 


Fig.  3.     Method  of  growing  plants  in  plant-house  to  determine  the 
amount  of  water  used. 

in  diameter  and  the  same  depth/  Tho  large  cylinders  this  year 
have  been  filled  with  a  black  marsh  soil,  and  the  small  ones  with 
a  virgin  soil  of  medium  clay  loam  variety,  taken  from  a  second - 
growth  black  oak  grove. 

First,  the  results  obtained  from  four  of  the  large  cylinders 
sowed  to  oats  Dec.  12,  1896,  and  harvested  July  1,  1897,  after  a 
period  of  200  days.  The  oats  were  sown  thick,  and  grew  very 
rank,  lodging  quite  badly. 

The  total  dry  matter  and  the  total  water  used  by  the  crop 
of  the  four  cylinders  was  as  given  below: 


36  Irrigation   and    Drainage 

No.  of  cylinders 18  14  23  24 

Dry  matter  produced-lbs 4  3.16         4.93  4.32 

Total  water  used— Ibs 1,808       1,668      2,061.5       1,782.5 

Dividing  the  amount  of  water  used  on  the  four  cylinders  by 
the  dry  matter  produced,  we  get,  as  the  mean  of  the  four  trials, 
under  the  conditions  of  the  plant-house,  446.1  pounds  of  water  for 
a  pound  of  dry  matter,  and  a  yield  of  dry  matter  per  acre  amount- 
ing to  12.645  tons,  which  is  very  large,  indeed.  The  water  used 
by  this  crop  expressed  as  rainfall  was,  as  a  mean  of  the  four 
trials,  49.76  inches.  Here  is  a  depth  of  water  used  from  this  soil 
which  is  a  little  greater  than  the  soil  itself  ;  but  the  rate  at  which 
the  water  was  used,  it  will  be  observed,  is  less  per  pound  of  dry 
matter  produced  than  that  for  the  out-of-door  experiments. 

In  the  case  of  the  clover  on  these  black  marsh  soils,  there 
were  eight  of  the  large  cylinders  used,  in  four  of  which  medium 
clover  grew,  and  on  the  other  four  alsike  clover.  These  were 
sown  without  a  nurse  crop,  and  at  the  same  time  as  the  oats,  but 
were  cut  July  8,  so  that  the  period  of  growth  was  207  days.  The 
results  obtained  here  with  medium  clover  were  as  stated  below  : 

No.  of  cylinders 15  16  21          22 

Dry  matter  produced— gms 507  608  620        573 

Water  used -Ibs 673.5        795.5        819        678 

Dividing  the  total  amount  of  water  used  on  the  four  cylinders 
by  the  total  dry  matter  produced,  we  get  582.9  pounds  of  water 
as  the  amount  used  per  pound  of  dry  matter.  In  this  case  the 
yield  of  dry  matter  per  acre  was  3.92  tons,  equal  to  4.61  tons 
of  hay  containing  15  per  cent  of  water.  The  amount  of  water 
used,  expressed  in  inches,  was  20.16. 

The  alsike  clover  gave  yields  and  results  as  follows: 

No.  of  cylinders 17  18  19         20 

Dry  matter  produced— gms 628         616         576        634 

Water  used— Ibs 809         758         774        804.5 

In  this  case,  the  mean  amount  of  water  for  a  pound  of  dry 
matter  was  581.5  pounds,  and  the  yield  of  dry  matter  per  acre 


Water    Used   by   Plants  37 

was  4.168  tons,  equal  to  4.9  tons  of  hay  containing  15  per  cent 
of  water.     The  water  used,  expressed  in  inches,  was  21.43. 

In  the  trials  of  clover  on  the  virgin  soil  in  the  plant-house, 
14  cylinders  of  the  smaller  size  were  used,  and  these  were  seeded 
Dec.  12,  1896,  and  cut  July  8,  1897.  The  yield  of  dry  matte*  in 
these  cases  per  unit  area  was  much  heavier  than  on  the  black 
soil,  the  amounts  standing  as  below: 


No.  of  cylinders  

71 

72 

73 

74 

75 

76 

77 

Dry  matter—  gms  

812.5 

315.5 

252.4 

230 

212.5 

244.5 

222.5 

Water  used—  Ibs  

373.5 

350 

206 

297 

292.5 

318 

295.5 

No.  of  cylinders  

78 

79 

80 

81 

82 

83 

84 

Dry  matter—  gms  

303.5 

223.5 

284.5 

292.6 

284.2 

277.5 

266.5 

Water  used—  Ibs  

351.5 

300.5 

311.5 

290 

326.5 

336 

347.5 

The  total  amount  of  water-free  dry  matter  produced  on  all 
the  cylinders  was  3,724.2  gms.,  or  8.215  pounds.,  using  4,496 
pounds  of  water,  or  at  the  rate  of  547.3  pounds  for  one  pound 
of  dry  matter.  The  average  yield  of  water-free  dry  matter  per 
acre  was  7.23  tons,  equal  to  8.51  tons  of  hay  containing  15  per 
cent  of  water.  The  water  used  during  the  207  days  from  seed- 
time to  cutting  of  the  first  crop  was  34.93  inches. 

Side  by  side  with  the  cases  now  cited,  six  other  cylinders 
were  planted  to  Rural  New-Yorker  potatoes  on  the  same  date. 
These  were  dug  July  2,  and  the  photo -engraving,  Fig.  4,  shows 
the  crop  produced.  Although  the  potatoes  were  planted  Dec.  12, 
they  did  not  come  up  until  into  February,  apparently  for  no  other 
reason  than  that  the  tubers  needed  a  certain  period  in  which  to 
develop  the  conditions  for  growth,  which  at  the  time  of  planting 
they  had  not  had.  When  the  plants  did  come  up  they  grew  very 
rapidly.  Below  are  given  the  results  of  these  trials: 


No.  of  cylinders 

65         66            67            68            69            70 

Weight  of  tubers  —  gms  

.     1,288  7    808  1     1,376        1,313.4    1,275.4    1,204.8 

1  168       732       1  249       1,189       1,155       1,091.5 

Total  dry  matter  —  gms  

342.6    263.6       332.5       334          312.2       328.8 

Water  per  Ib.  of  dry  matter  

275.4    347.6       281.7       272.3       307.3       306.3 
208       202           206.5       200.5       211.5       222 

Inches  of  water... 

22.63    21.98       22.47       21.81       23.01       24.15 

38 


Irrigation   and    Drainage 


Here,  again,  if  we  figure  the  yield  of  dry  matter  per  acre  on 
the  basis  of  the  amount  of  ground  occupied,  we  shall  have  the 
large  crop  of  8.67  tons  of  dry  matter  per  acre,  using  in  its  pro- 
duction 22.67  inches  of  water. 

In  twenty  other  18-inch  cylinders  in  the  plant-house,  a  variety 
of  white  dent  corn  was  grown,  four  plants  in  a  cylinder.  These 


Fig.  4.    Crop  of  potatoes  using  from  272-347  pounds  of  water  for  1 
pound  of  dry  matter. 

were  planted  May  22  and  harvested  Aug.  23,  and  on  the  twenty 
cylinders,  aggregating  35.34  square  feet  of  soil,  18.1  pounds  of 
dry  matter  were  produced,  which  used  5,685  pounds  of  water  in 
coming  to  maturity,  or  at  the  rate  of  314.1  pounds  of  water  for 
one  pound  of  dry  matter,  and  a  depth  of  water,  when  expressed 
as  rainfall,  of  30.93  inches,  the  yield  per  acre  being  22,310  pounds 
of  water -free  matter. 


Amount   of   Water    Used   ~by   Plants  39 

VARIATIONS    IN    THE    AMOUNT    OF    WATER    USED 
BY    PLANTS 

It  is  a  matter  of  very  fundamental  importance  to  know  what 
factors  or  conditions  may  cause  a  variation  in  the  amount  of  water 
which  is  necessary  to  produce  a  ton  of  dry  matter,  because  it  is 
only  by  knowing  these  that  it  will  be  possible  to  lay  down  any 
general  principles  for  determining  the  amount  of  water  which 
will  be  required  to  produce  a  given  yield. 

If  we  examine  the  data  which  have  been  presented,  it  will 
be  observed  that  not  only  is  there  a  rather  wide  variation  in  the 
amount  of  water  used  by  different  crops,  but,  also,  that  there  is, 
further,  a  wide  difference  recorded  as  occurring  with  the  same 
species  or  variety,  sometimes  with  the  same  species  in  the  same 
year,  and  sometimes  for  different  years,  and  it  is  important  to 
know  to  what  these  differences  are  due. 

In  the  case  of  corn,  for  example,  where  we  have  grown  it 
under  the  cylinder  conditions  in  the  field,  the  following  varia- 
tions have  been  noted : 

In  1891,  Pride  of  the  North  dent  corn  used  in  one  case  295.95 
pounds  qf  water  for  a  pound  of  dry  matter,  and  in  the  other  307.03 
pounds.  But  in  the  first  case  more  dry  matter  was  produced  by 
the  individual  plants,  the  first  producing  4.369  per  cent  more  than 
the  other  did,  but  in  doing  this  only  .602  per  cent  more  water 
was  taken  ;  that  is,  the  most  vigorous  plants  have  produced  the 
most  dry  matter  when  measured  by  the  amount  of  water  used. 
Indeed,  it  may  be  laid  down  as  a  general  rule,  that  the  more 
favorable  all  conditions  are  for  plant  growth,  the  more  effective 
will  be  the  water  supplied  to  the  crop.  Good  management,  there- 
fore, will  look  closely  to  all  details,  even  to  the  minor  ones, 
for  everything  counts  in  plant  feeding  just  as  it  does  in  animal 
feeding. 

Not  all  varieties  of  the  same  species  of  plant  use  water  in 
the  production  of  dry  matter  with  the  same  degree  of  effective- 
ness. In  our  work  with  dent  and  flint  corn,  for  example,  we  have 
found,  as  a  mean  of  four  trials,  that  Pride  of  the  North  dent 


40  Irrigation   and    Drainage 

corn  used  water  at  the  rate  of  309.84  pounds  of  water  per  pound  of 
dry  matter  produced,  and  25.74  inches  of  water  when  measured 
in  depth  on  the  area  occupied.  But  four  trials  with  a  variety  of 
flint  corn  gave  a  mean  of  233.9  pounds  of  water  per  pound  of  dry 
matter,  which  is  75.94  pounds  or  32.5  per  cent  less  than  in  the  case 
of  the  dent  variety.  This  is  not  because  actually  less  water  was 
used  per  unit  area,  for  the  flint  corn  in  these  four  trials  did  use 
a  mean  of  26.82  inches  against  25.74  for  the  dent  corn. 

It  seems  not  improbable  that  this  more  economical  use  of 
water  by  the  flint  corn  may  be  in  part  due  to  its  lower  habit  of 
growth  and  the  greater  abundance  of  foliage  closer  to  the  ground, 
for  it  may  be  expected  that  the  lower  position  of  the  leaves,  and 
their  crowding  as  well,  would  tend  to  lessen  the  amount  of 
evaporation  in  a  given  time.  But  to  whatever  the  difference  may 
be  due,  it  is  plain  that  on  light  soils  and  wherever  the  water 
supply  is  limited,  larger  returns  may  be  secured  by  paying  atten- 
tion to  the  variety  of  plant  grown. 

The  amount  of  water  used  by  a  particular  crop  might  be 
expected  to  vary  with  the  humidity  of  the  season  and  the  amount 
of  wind  movement  during  the  period  of  growth  of  the  crop  ;  but 
the  data  obtained  do  not  appear  to  show  so  marked  a  relation  as 
would  seem  should  exist.  The  mean  relative  humidity  of  the  air 
at  Madison  at  2  P.  M.,  in  1891,  for  June,  July  and  August,  was 
63.66  per  cent,  while  in  1892,  for  the  same  time  of  day  and  period, 
the  mean  was  68  per  cent  ;  and  the  total  wind  movement  for 
Madison,  these  years,  for  the  three  months,  as  given  by  the 
records  of  the  Washburn  Observatory,  was  20,712  miles  in  1891 
and  18,870  in  1892.  But  in  1891,  26.39  inches  of  water  gave  a 
yield  of  dry  matter  per  acre  of  19,845  pounds,  and  in  1892,  25.09 
inches  gave  a  yield  of  19,184  pounds  of  dry  matter  per  acre  of 
corn  in  the  plant  cylinders  in  the  field.  The  differences  in  the 
amounts  of  water  used  during  the  two  years,  it  will  be  seen,  is 
very  small,  especially  when  it  is  recognized  that  in  1892  the  dry 
matter  produced,  and  presumably  the  evaporation  surface  also, 
was  less  than  in  1891. 

So,  too,  in  the  case  of  oats  for  these  two  years,  19.60  inches 
of  water  gave  8,861  pounds  of  dry  matter  per  acre  in  1891,  and  in 


Amount   of   Water    Used   by   Plants  41 

1892,  19  inches  gave  8,189  pounds,  leaving  the  rate  of  evapo- 
ration from  the  plant  surface  very  nearly  the  same  for  the  two 
seasons,  in  spite  of  the  differences  of  humidity  and  of  wind 
velocities. 

In  the  case  of  barley  for  these  two  years,  there  was  a  wide 
difference  in  the  amount  of  water  used  per  unit  area,  13.19  inches 
being  used  in  1891  and  23.52  inches  in  1892.  But  the  yields  of  dry 
matter  per  unit  area  were  also  widely  different,  being  7,441  pounds 
of  dry  matter  per  acre  in  1891  and  14,196  pounds  in  1892.  The 
barley  in  1891  used  3.54  inches  of  water  per  ton  of  dry  matter, 
and  in  1892,  3.31,  or  only  .23  inches  less,  which  is  small. 

Even  when  the  conditions  are  as  different  as  those  in  the 
plant-house  and  the  open  field,  the  differences  are  not  as  marked 
as  we  were  led  to  expect,  as  the  table  which  follows  will  show: 


—  in  nem  —                 —  >    —  in  piani-nouse  — 
Acre-inches  of  water                                Acre-inches  of  water 
No.  of  trials     per  ton  of  dry  matter     No.  of  trials     per  ton  of  dry  matter 

Maize  

8 

2.433 

44 

2.386 

Oats  

8 

5.011 

12 

4.535 

Clover.  .. 

24 

5.345 

22 

5.005 

TotaJ 

40 

Mean      4.263 

Total      78 

Mean     3.975 

If  the  results  are  expressed  in  pounds  of  water  used  per 
pound  of  dry  matter,  then  they  stand  as  follows  : 

Pounds  of  water  per  Pounds  of  water  per 

No.  of  trials      pound  of  dry  matter      No.  of  trials     pound  of  dry  matter 

Maize....  8                              275.6  44  270.3 

Oats 8                              567.8  12  490.6 

Clover...  24                              605.5  22  567.1 

Total  40  Mean      483  Total      78  Mean      442.3 

The  tables  show  that  in  the  case  of  these  crops — maize,  oats 
and  clover— they  have  used  in  the  field  .288  acre -inches  of  water 
more  per  ton  of  dry  matter  produced  than  in  the  plant -house  ;  or, 
when  expressed  in  the  other  way,  40.7  pounds  of  water  per  pound 
of  dry  matter  more  in  the  field  cylinders  than  in  the  cylinders  in 
the  plant-house.  Expressed  in  percentages,  the  field  conditions 
demanded  9.2  per  cent  more  water  when  the  cylinders  stood  out- 


42  Irrigation   and    Drainage 

of-doors,  with  the  plants  surrounded  by  the  field  crop  and  under 
the  out-of-door  meteorological  conditions,  than  they  did  in  the 
house. 

This  difference,  however,  shows  larger  than  it  really  is,  for  it 
has  been  shown  that  the  use  of  water  is  usually  more  economical 
in  those  cases  in  which  the  yields  are  largest,  and  in  these  cases 
there  has  been  a  larger  yield  of  dry  matter  per  unit  area  in  the 
plant-house  cylinders  than  were  secured  from  the  cylinders  in  the 
field.  The  total  mean  yield  per  acre  for  the  oats,  maize  and 
clover  in  the  field  cylinders  was  6.312  tons  and  in  the  plant-house 
7.397  tons  of  dry  matter  per  acre,  making  the  latter  yields  on  the 
average  17.19  per  cent  larger;  and  to  this  difference  in  yield  must 
certainly  be  ascribed  a  part  of  the  difference  in  the  amount  of 
water  given  off  from  the  plants  and  from  the  soil  during  the 
periods  of  growth.  It  is  quite  plain,  for  example,  that  the  loss 
of  water  from  the  soil  surface  would  tend  to  be  relatively  larger, 
and  probably,  also,  absolutely  larger  from  the  cylinders  bearing 
the  smallest  crop  of  a  given  kind.  The  absolute  loss  would  cer- 
tainly be  largest  from  the  cylinders  where  the  crop  had  the  thin- 
nest stand  on  the  ground,  and  some  of  the  cases  of  larger  yield 
per  unit  area  in  the  plant-house  are  due  to  the  fact  that  more 
plants  occupied  the  same  area. 

While,  therefore,  from  the  general  principles  governing  the 
rate  of  evaporation,  we  are  led  to  expect  that  more  moisture  must 
be  lost  from  vegetation  growing  in  a  dry  atmosphere  than  under 
more  humid  conditions,  we  are  not  able  to  point  to  our  data  as 
bearing  out  such  a  view  in  any  emphatic  manner.  The  rate  of 
air  movement  in  the  plant-house  has  certainly  been  less  than  it 
was  in  the  field,  but  the  higher  temperature  in  the  plant-house 
has  probably  left  the  air  relatively  dryer  during  both  day  and 
night  than  in  the  field. 

The  conditions  which  did  exist,  both  in  the  plant-house  and 
in  a  field  of  maize,  were  noted  on  July  27,  28  and  29.  The  rela- 
tive humidity  of  the  air  was  measured  with  a  wet-and-dry  bulb 
thermometer,  and  the  rate  of  evaporation  was  also  measured  under 
the  two  conditions  with  a  form  of  Piche  evaporometer.  Two  of 
these  instruments  were  hung  among  the  corn  plants  in  the  plant- 


Amount   of   Water    Used   by   Plants  43 

house  and   two  others  in  the  field,  one  pair  on  irrigated  ground 
and  the  other  on  ground  not  irrigated. 

The  table  below  shows  the  variations  in  the  rate  of  evapora- 
tion observed  in  the  three  localities  : 

Plant  house          Irrigated  field        Field  not  irrigated 
No.  1         No.  2        No.  1        No.  2  No.  1      No.  2 


c.  e. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

July  27  

....        7 

5.8 

6.3 

4.03 

6.86 

4.2 

•July  2S 

5  75 

4.35 

2.95 

3.13 

4.87 

3.C6 

.Inly  29  

5.46 

5.6 

5.96 

5.7 

6.1 

5.76 

Mean  .  .  . 

6.035 

5.25 

4.98 

4.287 

5.94 

4.34 

These  rates  of   evaporation   took  place  upon  a  surface  of   27 
square  inches  of  wet  filter  paper. 

The  relative  humidity  observations  were  as  here  given: 

Plant-house        Irrigated  field        Field  not  irrigated 


July  27  '.  

PER  CENT 
38 

PER  C 
45 

ENT 
51 

PER  CENT 
49         55 

July  28 

39  5 

54 

55 

57         62 

July  29  

41 

49 

52 

48.5      49 

Mean  .  . 

39.5 

49.3 

52.7 

51.5       55.3 

80  far  as  these  figures  may  be  relied  upon,  it  would  appear 
that  the  rate  of  evaporation  in  the  plant -house  may  even  have 
exceeded  that  in  the  field,  and  if  this  was  true  during  the  time  the 
dry  matter  of  the  plant-house  experiments  was  being  produced, 
then  the  indications  are  still  less  marked  pointing  toward  an 
increase  in  the  amount  of  water  being  required  for  a  pound  of 
dry  matter  in  a  dry,  rapidly  changing  atmosphere,  than  is 
required  under  stiller  and  more  humid  conditions. 

It  may  be  true  that  in  the  dry  air  a  more  rapid  loss  of  mois- 
ture from  the  plant  does  take  place,  and  that  this  loss  stimulates 
a  proportional  increase  of  dry  matter.  This  is  merely  a  suppo- 
sition, however,  with  no  experimental  evidence  to  bear  it  out, 
but  such  a  tendency  would  give  relations  approaching  those 
recorded  above.  So,  too,  if  the  rate  of  evaporation  is  automatic 


44  Irrigation   and    Drainage 

ally  controlled  by  changes  in  the  transpiring  surfaces  of  plants, 
and  if  this  control  is  sensitive,  then  there  would  also  be  a  ten- 
dency to  cause  the  amount  of  water  necessary  to  produce  a  pound 
of  dry  matter  in  a  given  species  of  plant  to  remain  nearly  con- 
stant under  wide  ranges  of  climatic  conditions.  That  most  land 
plants  are  provided  with  organs  which  modify  the  rate  of  trans- 
piration has  been  long  established  ;  but  how  narrow  the  limits 
of  control  are  remains  to  be  demonstrated.  It  is  fundamentally 
very  important  that  such  facts  as  these  should  be  established,  for 
they  are  needed  in  order  that  we  may  know  how  much  land  under 
a  given  crop  a  given  quantity  of  water  will  irrigate. 

We  have,  at  this  writing,  just  completed  a  set  of  observations 
bearing  upon  this  fundamental  problem,  and  although  they  are 
not  sufficiently  extended  to  be  demonstrative,  they  are  yet  very 
suggestive,  and  will  be  of  interest  here. 

If  it  is  true  that  plants  lose  little  moisture  except  through 
their  breathing  pores,  and  if  these  are  closed  during  those  times 
when  there  is  not  sufficient  light  to  allow  carbonic  acid  gas  to  be 
decomposed  by  the  plant,  then  during  the  night,  and  perhaps, 
also,  during  cloudy  weather,  plants  should  lose  but  little  moisture 
through  their  surfaces.  To  test  this  question,  one  of  the  small 
cylinders  in  the  plant -house,  containing  four  fully  grown  stalks 
of  maize,  was  hung  upon  the  scales,  to  be  weighed  hourly  dur- 
ing the  day  ;  and  by  the  side  of  it  was  set  a  Piche  evapo- 
rometer  having  an  evaporation  surface  of  27  square  inches,  also 
to  be  read  hourly.  Below  are  given  the  results  of  these  obser- 
vations : 

During  the  day,  from  8:15  A.  M.  until  6:15  p.  M.,  it  was  some- 
what cloudy  most  of  the  time,  but  the  clouds  were  not  heavy,  and 
there  was  a  little  sunshine  through  a  haze  from  11:15  A.  M.  until 
2:15  P.  M.  From  8:15  A.  M.  until  6:15  P.  M.  the  corn  and  soil 
lost  3  pounds  of  water,  and  there  was  evaporated  from  the  evaporo- 
meter  31.5  c.  c.  or  1.2  cu.  in.  From  6:15  P.  M.  until  6:45  A.  M. 
the  next  morning,  the  corn  had  not  lost  enough  to  show  on  the 
scales,  which  are  sensitive  to  one -half  pound  ;  and  the  evaporo- 
meter  showed  a  loss  of  2.3  c.  c.,  equal  to  .14  cu.  in.  The  next 
day  was  bright  and  sunny  the  whole  time,  and  from  6:45  A.  M. 


Transpiration    Greatest    During    Sunshine         45 

until  6:15  P.  M.  the  maize  lost  7.5  pounds  of  water  and  the 
evaporometer  lost  67.5  c.  e.,  or  4.12  cu.  in. ;  but  during  the  night 
again  the  loss  from  the  maize  was  too  small  to  be  measured, 
while  the  evaporometer  showed  a  loss  of  4.6  c.  c.,  equal  to  .28 
cu.  in. 

On  the  next  day,  Aug.  9,  all  of  the  cylinders  in  the  plant- 
house  were  weighed  during  the  forenoon,  which  was  cloudy,  but 
in  the  afternoon  it  cleared  and  the  sun  shone  brightly.  During 
the  whole  of  the  afternoon  and  until  9  P.  M.  we  forced  steam  from 
the  boiler,  under  a  pressure  of  7  to  15  pounds,  into  the  plant-house 
through  an  inch  pipe  wide  open,  and  kept  the  house  closed 
through  the  experiment.  Steam  filled  the  whole  plant-house  and 
condensed  upon  the  glass  and  walls,  dripping  in  many  places  from 
the  roof. 

On  the  following  morning,  Aug.  10,  a  number  of  the  cylinders 
were  again  weighed,  to  see  if  there  had  been  any  loss  of  water 
from  the  plants,  and  it  was  found  that  three  of  the  small  clover 
cylinders  had  lost  an  average  of  2  pounds  each,  while  their  mean 
loss  during  the  seven  preceding  days  had  been  at  the  rate  of  2f 
pounds.  Eight  stalks  of  maize  in  a  large  cylinder  lost  7  pounds, 
while  its  mean  loss  per  day  had  been  6f  pounds.  Six  small  cylin- 
ders, each  containing  4  stalks  of  maize,  lost  an  average  of  4| 
pounds  each,  while  the  mean  loss  for  the  week  had  been  4| 
pounds. 

It  thus  appears  that  during  the  night  and  cloudy  weather 
plants  lose  but  little  moisture,  but  that  when  the  sun  shines 
brightly,  even  in  an  atmosphere  nearly  saturated  with  moisture, 
there  is  a  very  marked  loss  of  water  from  the  growing  plants, 
and  it  would  appear  that  the  amount  is  nearly  or  quite  as  large 
in  a  damp  as  in  a  dry  air.  These  observations  seem  strange, 
and  need  to  be  confirmed  ;  but  they  are  in  harmony  with  our 
observations  regarding  the  amount  of  water  required  for  a  pound 
of  dry  matter. 

If  we  bring  together  all  of  the  observations  made  in  Wiscon- 
sin on  the  amount  of  water  used  in  the  production  of  dry  matter 
by  plants,  they  will  stand  as  in  the  table  which  follows  : 


46  Jt-riyntion   and    Drainage 

Table  shoiviny   the   mean  amount  of  water  used  by  various  plants  in  Wisconsin 
in  producing  a  ton  of  dry  matter 

Water  required  to  Dry  matter  Acre-inches  of 

^o.  of       P''°'lwe  1  lb.  of  Water  used  produced  water  per  ton  of 

trials              *? 111!itter  INCHES  TONS  dry  matter 

Barley....        5                    464.1  20.69  5.05  4.096            4 

Oats 20                   503.9  39.53  8.89  4.447 

Maize 52                   270.9  15.76  6.59  2.391 

Clover....       46                    576.6  22.34  4.39  5.089 

Peas 1                   477.2  16.89  4.009  4.212 

Potatoes..       14                    385.1  23.78  6.995  3.399 

Total    138  Average  446.3  23.165  5.987  3.939 

In  computing  the  results  in  this  table,  the  combined  area  of 
all  cylinders,  the  combined  weights  of  dry  matter  produced,  and 
the  combined  amounts  of  water  used,  have  been  divided  by  the 
number  of  trials  with  each  kind  of  crop  and  the  average  results 
used  in  making  the  calculations. 

In  considering  these  results,  it  should  be  kept  in  mind  that 
the  water  used  by  the  several  crops  is  made  to  include  that  which 
was  lost  through  the  soil  by  surface  evaporation,  because  it  was 
not  easy  to  measure  this  separately  or  to  prevent  it  without  intro- 
ducing abnormal  conditions.  It  is  quite  certain,  however,  that 
during  all  of  these  trials  the  rate  of  loss  from  the  soil  has  been 
somewhat  less  than  would  have  occurred  under  the  best  possible 
management  with  field  conditions. 

Attention  should  be  called  to  the  fact,  also,  that  the  large 
amount  of  water  used,  averaging  for  the  138  trials  23.165  inches, 
is  greater  than  field  conditions  would  demand,  if  nothing  were 
lost  by  percolation,  for  the  reason  that  we  have  planted  so  as  to 
utilize  less  surface  area  than  is  the  practice  in  the  field  ;  and  it  is 
to  this  fact,  also,  that  the  very  large  average  yields,  when  com- 
puted per  acre,  are  due,  rather  than  to  the  growth  of  plants  of 
abnormal  size. 

THE     MECHANISM     AND    METHOD     OF    TRANSPIRATION 
IN    PLANTS 

Since  water  plays  so  large  a  part  in  the  life  and  develop- 
ment of  land  plants,  and  since  such  large  quantities  of  it  are 


Mechanism   of  Transpiration  47 

used  by  them,  it  will  be  very  helpful  to  know  in  what  manner 
thts  water  is  moved  through  and  from  the  plant,  and  just  what 
part  it  plays  in  plant  life. 

We  may  understand  the  essentials  of  this  complex  process 
best  if  we  compare  it  with  our  own  breathing  ;  for  transpiration 
and  respiration  of  land  plants  have  much  in  common  with  the 
breathing  of  animals.  Bot-h  the  plant  and  animal  breathe  air,  and 
while  breathing  it,  both  give  off  large  quantities  of  water  from  the 
organs  of  respiration.  If  you  hold  a  cold,  clean  mirror  in  front 
of  a  person  breathing,  its  surface  becomes  at  once  clouded  with 
the  moisture  from  the  breath.  So,  too,  if  you  hold  the  same 
cold  mirror  close  to  the  foliage  of  a  growing  plant,  the  moisture 
escaping  from  that  will  also  cloud  the  mirror. 

Now,  the  primary  object  of  the  lungs  in  our  case  is  not  to 
remove  water  from  the  system,  but  to  provide  a  means  for  oxy- 
gen to  enter  the  blood  from  the  air,  and  for  the  carbonic  acid 
gas  to  escape  from  the  blood  into  the  air.  This  can  take  place 
rapidly,  however,  only  when  the  delicate  lining  of  the  air  cells 
in  the  lungs  is  kept  moist  ;  and  so  the  chief  function  of  the 
water  escaping  from  the  lungs  is  to  maintain  their  inner  surface 
continually  wet.  Let  the  lung  lining  once  become  dry,  and  the 
rate  at  which  oxygen  could  enter  and  carbonic  acid  gas  escape 
from  the  blood  would  be  so  slow  that  life  could  not  be  main- 
tained ;  and  in  order  that  this  fatal  accident  shall  not  occur,  the 
lung  surface  is  placed  on  the  inside  of  the  chest,  where  the  rate 
of  evaporation  is  very  greatly  impeded. 

When  we  turn  to  the  breathing  of  plants,  we  find  that  they, 
too,  are  only  able  to  accomplish  that  very  important  work  as 
rapidly  as  it  needs  to  be  done  by  having  a  very  broad  surface 
against  which  the  air  may  come,  but  so  placed  that  it  shall  be 
kept  always  wet  ;  and,  just  as  in  our  case,  it  would  never  do  to 
have  this  surface  exposed  to  the  open  air,  so  the  real  breathing 
surface  of  plants  is  spread  out  on  the  inside  of  their  structure, 
where  hot,  strong  winds  can  never  reach  it. 

In  Fig.  5  is  represented  a  piece  of  a  barley  leaf,  partly  dis- 
sected and  much  magnified,  which  shows  the  breathing  surface  of 
this  plant,  and  how  it  is  protected  from  excessive  evaporation 


48 


Irrigation   and    Drainage 


In  the  upper  part  of  the  figure,  the  under  surface  of  the  leaf 
is  shown  covered  by  its  skin  or  epidermis,  through  which  there 
can  but  little  evaporation  take  place  except  through  the  opening 
which  is  shown  at  sp  and  the  seven  others  like  it  ;  and  even 

these  openings  or  breathing 
pores  are  so  made  that  they 
may  be  automatically  opened 
wide  or  almost  completely 
closed  when  the  needs  of  the 
plant  call  for  much  or  little 
air. 

In  the  lower  part  of  the 
figure,  the  skin  has  been  re- 
moved from  the  leaf,  so  as  to 
show  the  actual  breathing  sur- 
face of  the  barley  plant,  con- 
sisting of  the  cells  marked  w, 
and  which  are  filled  with  the 
green  coloring  matter  of  the 
leaf,  or  chlorophyll.  The  open 
spaces,  marked  i,  between  the 
breathing  cells,  are  the  breath- 
ing or  respiratory  chambers, 
which  communicate  with  one 
another  all  through  the  leaf, 


Pig.  5.  Structure  of  barley  leaf.  (After 
Sorauer.)  sp  is  a  breathing-pore;  m, 
chlorophyll  cells ;  i,  respiratory  cham- 
bers. 


but  under  the  cover  of  its 
skin  or  epidermis,  which  in  various  ways,  by  a  varnish,  a  wax  or 
a  close  mat  of  hairs,  is  rendered  less  pervious  to  water  and 
to  air.  In  the  case  of  tall  plants,  like  shrubs  and  forest 
trees,  rising  a  hundred  and  more  feet  into  the  air,  nature  has 
made  still  greater  efforts  to  avert  the  danger  of  plants  being 
destroyed  by  the  action  of  drying  winds.  Here  we  find  the 
trunks  and  all  the  larger  limbs  thoroughly  protected  by  a  thick 
bark,  through  which  there  can  but  little  water  escape  as  it  slowly 
ascends  from  the  roots  to  the  leaves  ;  indeed,  the  more  detailed 
we  make  the  study  of  the  structure  and  the  function  of  parts  in 
the  plant,  the  more  plain  it  becomes  that  in  most  land  plants  the 


Magnitude   of  Transpiration  49 

greatest  economy  is  everywhere  practiced  in  regard  to  the  use  of 
water. 

If  it  were  true  that  no  water  need  be  used  by  plants  except 
that  which  is  assimilated  during  their  growth  and  reproduction,  and 
in  keeping  the  cells  distended  and  turgid,  so  that  wilting  shall 
not  occur,  then  there  would  be  little  need  for  irrigation  anywhere 
except  in  the  most  arid  of  arid  regions,  for  then  even  the  hygro- 
scopic moisture  of  a  dry  soil  would  be  sufficient  in  quantity  to 
supply  the  demands  of  almost  any  land  plant. 

The  facts  are,  however,  that  during  the  hours  of  sunshine  all 
growing  plants  which  feed  directly  upon  soil  and  air  must  have 
their  assimilating  chlorophyll-bearing  cells  continually  in  contact 
with  a  changing  volume  of  air,  in  order  that  the  carbon,  which 
makes  up  so  large  a  part  of  their  dry  weight,  may  be  obtained  in 
sufficient  quantity  from  the  carbonic  acid  gas  in  the  atmosphere. 
But  the  more  recent  analyses  of  air  show  that  on  the  average  it 
contains  but  one  part  of  carbonic  acid  by  weight  in  2,000  parts. 
Now,  how  much  air  must  a  field  of  clover  breath  in  order  that 
it  may  produce  two  tons  of  hay  per  acre  ?  Let  us  see. 

Boussingault  found  by  analysis  that  4,500  pounds  of  clover 
hay  harvested  from  an  acre  of  ground  contained  no  less  than  1,680 
pounds  of  carbon,  and  as  this  was  derived  almost  wholly  from  the 
carbonic  acid  of  the  air,  it  must  have  decomposed  6,160  pounds 
of  carbonic  acid  in  order  to  procure  it.  But  as  there  is  only 
one  pound  of  carbonic  acid  in  2,000  of  air,  it  follows  that 
12,320,000  pounds  of  air  must  have  yielded  up  the  whole  of  its 
carbonic  acid  gas  in  order  to  supply  the  needed  amount  of  carbon. 
Now,  one  cubic  foot  of  air  at  a  pressure  of  29.922  inches  and 
at  a  temperature  of  62°  F.  weighs  .080728  pounds,  and  this  being 
true,  not  less  than  152,600,000  cubic  feet  of  air  must  have  been 
required  to  meet  the  demands  of  this  clover  field  for  carbonic 
acid.  This  amount  of  air  would  cover  the  acre  to  a  depth  of 
.'3,503  feet,  having  a  uniform  normal  density. 

Of  course,  not  all  of  the  carbonic  acid  in  the  air  which 
passes  across  a  clover  field  can  be  secured,  nor  indeed  all  of 
that  which  enters  the  intercellular  air  passages  of  the  green 
parts  of  the  plant/  and  hence  it  follows  that  very  much  larger 

D 


50  Irrigation  and   Drainage 

volumes  of  air  than  have  been  stated  must  be  brought  into  close 
contact  with  the  growing  clover  in  order  to  meet  its  needs.  This 
air,  however,  cannot  come  into  intimate  relations  with  the  green 
chlorophyll-bearing  cells  of  the  clover  in  the  field  without  of 
necessity  permitting  the  evaporation  of  large  quantities  of  water 
from  the  plants  ;  and  this  brings  us  to  realize  how  imperative  is 
the  demand  for  water  by  rapidly  growing  crops. 

The  writer  has  found,  for  example,  by  direct  measurement, 
that  the  air  passing  three  feet  above  a  clover  field,  and  at  a 
moderate  rate,  even  as  early  as  May  30  in  Wisconsin,  when  the 
air  temperature  is  only  52.48°  F.,  may  have  its  relative  humidity 
increased  from  44  to  48  per  cent  by  the  moisture  taken  from  the 
field  ;  and  this  means  that  3,510  pounds  of  water  are  required  to 
make  even  the  observed  change  of  humidity  in  a  volume  of  152,- 
600,000  cu.  ft.  of  air,  which  is  the  amount  required  to  carry  to 
the  clover  crop  its  carbon,  supposing  all  the  carbon  which  the  air 
contained  to  be  utilized.  It  is  quite  likely,  however,  that  the 
volume  of  air  which  did  contribute  its  carbon  to  Boussingault's 
crop  of  clover  not  only  exceeded  fourfold  the  amount  stated 
above,  but  that  it  also  had  its  relative  humidity  raised  at  least 
to  94  per  cent.  If  these  suppositions  are  true,  then  the  amount 
of  water  borne  away  from  the  plants  in  question  must  have  ex- 
ceeded 176,100  pounds,  or  at  the  rate  of  about  40  pounds  of  water 
for  a  pound  of  dry  matter  ;  but  it  has  been  shown  on  a  preceding 
page  that,  as  a  mean  of  46  trials,  the  clover  crop  did  lose  from  its 
tissues  and  from  the  soil  in  which  it  grew  576.6  pounds  of  water 
per  pound  of  dry  matter  produced,  so  that,  large  as  are  the 
figures  stated  above,  they  fall  far  below  the  actual  ones. 

With  these  estimates  and  considerations  before  us,  we  can 
readily  understand  that  one  of  the  chief  functions  of  water  in 
plant  life  is  to  keep  the  tissues  moist  and  in  a  suitable  condition 
to  carry  on  the  process  of  breathing,  whose  primary  object  is  to 
get  the  plant  its  carbon  from  the  air. 

In  order  that  the  plant  may  utilize  the  carbon  of  the  car- 
bonic acid  in  the  air,  it  is  necessary  that  this  should  come  to 
the  chlorophyll-bearing  cells  when  there  is  sunshine  enough  to 
decompose  it ;  and  since  the  carbonic  acid  would  be  useless  at 


Control   of   Transpiration  51 

other  times,  and  since  the  continual  ingress  and  egress  of  the  air 
which  brings  it  would  entail  a  steady  drain  of  moisture  from  the 
plant  by  evaporation,  the  breathing  pores  in  the  leaves  are  usu- 
ally provided  with  a  pair  of  guard  cells,  which  are  so  constituted 
that  they  may  be  opened  and  closed,  and  thus  exclude  nearly  all 
the  air  from  the  interior  of  the  plant  ;  or,  by  partly  closing 
them,  to  vary  the  amount  of  air  which  may  be  admitted  in  a 
given  time. 

In  order  that  the  escape  of  moisture  from  the  plant  may  be 
as  little  as  possible  when  the  breathing  pores  must  be  open  to 
admit  air,  the  great  majority  of  them  are  placed  on  the  under  or 
shaded  side  of  the  leaf.  Thus  Goodale,  quoting  from  Weiss, 
gives  in  a  table  the  number  of  breathing  pores  observed  per 
square  millimeter  of  surface  on  both  the  under  and  the  upper 
surfaces  of  the  leaves  of  forty  species  of  plants,  from  which  it  is 
computed  that,  on  the  average  in  these  cases,  there  are  209 
breathing  pores  on  the  lower  side  of  the  leaf  for  every  51  on  the 
upper  side.  How  numerous  and  how  minute  these  openings  are 
may  be  appreciated  when  it  is  said  that  in  the  forty  cases  cited 
there  are,  on  the  average,  209,000  stomata  on  each  area  the  size 
of  the  square  in  Fig.  6,  on  the  under  sides  of  the  leaves  of  these 
species.  Taking  a  specific  case,  that  of  corn,  Zea  Mays,  it  is 
stated  that  the  breathing  pores  number,  on  the  under  side  of  the 
leaf,  158,  and  on  the  upper  side  94,  or  in  all  252  for  each  square 
millimeter  of  leaf,  and  that  the  combined  area  of  these  openings 
is  .2124  of  a  square  millimeter,  so  that  21  per  cent  of  the  leaf 
surface  of  corn  is  made  up  of  doorways  through  which  air  may 
reach  the  interior  of  the  plant,  and  out  of  which  moisture  must 
escape  whenever  they  are  open. 

It  is  not  strange,  therefore,  that  large  amounts  of  mois- 
ture do  escape  from  plants  while  they  are  growing,  nor  that  there 
has  been  provided  a  means  of  checking  this  loss  as  far  as  pos- 
sible. 

The  opening  and  closing  of  the  guard  cells  is  brought  about 
by  changes  in  the  quantity  of  material  which  they  contain,  caus- 
ing them  to  open  when  the  cells  become  distended  and  to  close 
when  they  again  become  limp.  Unlike  the  other  ce"lls  in  the 


52  Irrigation  and   Drainage 

epidermis  of  the  leaf,  these  guard  cells  of  the  breathing  pores 
contain  chlorophyll  grains,  and  are  thus  able,  in  the  sunshine,  to 
decompose  carbonic  acid  and  carry  on  the  processes  of  building 
plant -food  ;  but  the  very  fact  that  food  is  being  elaborated  in 
these  cells  causes  the  sap  in  them  to  become  more  dense,  and 
this,  in  its  turn,  causes  water  from  the  direction  of  the  roots  to 
enter  these  cells  more 'rapidly  than  the  elaborated  materials  es- 
cape, and  so  to  distend  them,  and  open  wide  the  breathing  pores 
just  at  the  time  when  air  should  be  admitted  to  the  interior  of 
the  leaf.  But  just  as  soon  as  the  stimulating  effect  of  sunlight 
becomes  too  feeble  to  allow  work  to  be  done  in  them,  then  both 
on  account  of  the  elastic  tension  of  these  cell  walls  and  because 
of  the  diminished  osmotic  pressure  toward  the  guard  cells,  more 
fluid  escapes  from  them  than  enters  them  in  a  given  time  ;  they 
become  limp,  and  their  concave  faces  flatten  and  approach  each 
other,  thus  shutting  off  the  entrance  of  air  to  the  interior  of  the 
leaf  and  at  the  same  time  reducing  the  loss  of  water  to  the 
mininum. 

Again,  if  the  soil  moisture  becomes  insufficient  to  meet  the 
demands  of  the  plant,  or  if  hot,  drying  winds  take  away  the 
moisture  from  the  leaves  faster  than  osmotic  pressure  can  supply 
it  from  the  roots,  then  these  guard  cells  are  in  the  very  position  to 
be  most  and  first  affected  by  the  shortage  of  water,  and  hence  are 
where  they  will  collapse  and  check  the  loss  from  the  leaf  surface. 
But  just  as  assimilation  cannot  go  on  in  the  absence  of  sunlight, 
so  it  cannot  go  on  properly  in  the  presence  of  sunshine  if  there 
is  a  great  deficiency  of  water;  and  hence  we  see  that  the  guard 
cells  are  so  conditioned  that  they  will  shut  off  the  air  from  the 
interior  of  the  plant  at  just  those  times  when,  if  it  could  be 
changing,  it  would  be  doing  an  injury  by  wasting  moisture,  which 
is  so  indispensable  to  growth,  and  which  it  is  usually  really  dif- 
ficult for  plants  to  get  enough  of  to  insure  their  most  rapid  and 
complete  development. 

The  mechanical  principle  upon  which  the  guard  cells  are 
opened  and  closed  may  be  readily  understood  from  Fig.  6.  For 
simplicity  in  illustrating  the  principles,  let  A,  B,  C,  D  represent 
four  views  of  a  pair  of  guard  cells,  A  being  the  pair  with  the 


Control   of   Transpiration 


53 


mouth  open,  but  with  their  two  ends  abutting  against  each  other 
and  pressing  firmly  with  their  backs  against  the  surrounding  tis- 
sue of  the  leaf,  3-4  ;  B  is  a  cross -section  of  these  cells  along  the 


Fig.  6.  Diagram  showing  the  mechanical  action  of  guard  ceils  in  opening  and 
closing  breathing  pores.  The  square  shows  the  area  of  under  side  of  leaf 
containing  an  average  of  209,000  breathing  pores  or  stomata. 

line  1-2  ;  while  C  and  D  are  corresponding  views  with  the  breath- 
ing pore  closed.  It  will  readily  be  seen  that  if  the  water  holding 
the  two  cells  in  A  and  B  rigid  and  distended  partially  escapes 
from  them,  their  thin  walls  will  then  fall  down  and  take  the 
positions  shown  in  C  and  D,  where,  as  no  displacement  can  take 
place  in  the  directions  away  from  the  opening  on  account  of  the 
surrounding  tissue,  the  walls  must  advance  toward  each  other, 
more  or  less  completely  closing  the  aperture  between  them,  as 
shown  at  C  and  D.  Then,  too,  when  the  cells  again  become  dis- 
tended and  turgid,  the  pressure  will  tend  to  force  them  to  take 
the  circular  outline  shown  in  section  at  B,  and  as  the  back  wall 
of  the  two  is  fixed  to  the  tissue  so  as  not  to  be  able  to  move, 
nearly  all  of  the  motion  takes  place  upward  and  downward,  and 
this  pulls  the  two  faces  which  are  not  fixed  away  from  each  other 
and  widens  the  stoma  or  pore.  It  must,  of  course,  be  kept  in  mind 
that  the  shape  of  the  actual  guard  cells  varies  in  detail  in  many 
ways  from  the  diagram  given,  and  that  we  have  here  only  intended 
to  illustrate  the  mechanical  principle  involved  in  their  opening 
and  closing. 

We  see,  then,  that  not  only  is  water  a  very  important  sub- 


54  Irrigation  and   Drainage 

stance  in  the  economy  of  plant  life,  and  large  quantities  of  it  are 
used,  but  that  it  is  so  difficult  to  always  procure  enough  that 
nature  has  provided  in  the  organization  of  the  plant  that  none 
be  wasted  unnecessarily.  It  must  be  very  evident,  also,  that 
whatever  we  may  do,  in  our  methods  for  growing  crops,  to  keep 
the  plants  so  fully  supplied  with  moisture  that  they  shall  be  able 
to  utilize  all  the  sunlight,— by  keeping  their  breathing  pores 
wide  open,  so  that  all  air  which  can  be  used  will  be  supplied, — 
must  tend  to  give  us  larger  yields. 


THE    MECHANISM    BY    WHICH     LAND    PLANTS    SUPPLY 
THEMSELVES    WITH    MOISTURE 

So  long  as  plants  maintained  a  simple,  or  relatively  few-celled 
structure,  and  especially  so  long  as  they  lived  wholly  or  largely 
immersed  in  water,  it  was  an  easy  matter  for  them  to  be  supplied 
with  as  much  water  as  they  needed  by  simple  diffusion  and 
osmosis,  just  as  the  dry  bean,  when  put  to  soak,  swells  and 
becomes  turgid  by  the  water  which  has  been  driven  into  its  cellu- 
lar structure  under  the  ceaseless  hammering  impulses  of  heat. 
But  when  the  time  came  for  plants  to  abandon  the  water  and  to 
occupy  the  land  with  their  varied  forms,  and  especially  when  that 
race  began  for  free  air  and  direct  sunshine  which  led  on  from 
herb  to  shrub,  and  through  arborescent  forms  to  the  giant  forest 
trees,  then  it  became  necessary  for  that  complex  and  wonderful 
system  of  water -works  which,  with  its  intakes  in  the  form  of  roots, 
spread  out  in  a  comparatively  dry,  well -drained  soil,  is  able  to 
gather  from  off  the  damp  surfaces  of  soil  grains  and  send  to  a 
height  of  a  hundred  feet  a  stream  which,  when  divided  between 
ten  thousand  leaves,  shall  yet  have  volume  and  pressure  enough 
to  keep  them  turgid  in  a  strong,  drying  wind  and  a  hot  sun. 
Man,  with  his  mechanical  skill  and  inventive  genius,  has  been 
able  to  install  pumping  plants  which  can  lift  more  water  to  a 
greater  height  in  a  shorter  time  ;  but  to  do  this  he  has  been 
forced  to  station  himself  by  a  running  stream,  or  to  import  his 
energy  at  a  great  cost  ;  while  the  land  plant,  independent  of  wind 


Absorbing    Surfaces   of  Roots  55 

and  water  and  coal,  stations  itself  in  any  fertile  soil,  and  does  its 
work  with  the  warmth  of  a  summer  day. 

In  all  our  problems  of  land  drainage  and  irrigation,  we  are 
searching  to  better  understand,  and  through  this  better  under- 
standing to  better  meet,  the  conditions  under  which  a  system  of 
roots  can  best  do  its  work.  But  thf  foundation  of  such  an  under- 
standing should  be  a  knowledge  of  the  root  itself,  and  how  it 
places  itself  in  the  soil  in  order  that  it  may  do  its  work.  Let  us 
attempt,  then,  to  present  in  a  brief  form  what  has  been  learned 
regarding  the  essential  features  of  root  structure  and  root  action. 

Roots  have  three  distinct  functions  to  perform  in  land  plants 
having  green  leaves  :  first,  to  absorb  moisture  and  the  salts  held 
in  solution  ;  second,  to  convey  and  deliver  into  the 
stem  of  the  plant  the  water  which  has  been  absorbed : 
and  third,  to  act  as  a  support  to  the  plant  and  hold 
it  upright  in  the  air  and  sunshine,  whenever  it  is 
not  trailing  or  climbing  in  habit,  or  is  without 
stems. 

It  appears  to  be  the  general  conviction  among 
plant  physiologists  that  only  the  very  tip  ends  of 
the  roots  are  particularly  serviceable  as  absorbing 
agents,  and  that  even  these  are  serviceable  fo'r  a 
short  time  only.  Farther  than  this,  it  is  the  root- 
hairs  which  branch  out  in  great  numbers  from  them, 
rather  than  the  fine  roots,  which  are  the  real  ab-  Q  . 

sorbing  surfaces.      These    root-hairs  are  extremely 

u        Fig.7.  Root-hairs 
delicate,   thin-walled  tubes,  usually  not  more  than    ot-     mustard 

one -eighth  of  an  inch  long  and  a  hundredth  of  an  plants,— A  with 
inch  or  less  in  diameter,  which  stand  out  on  the  B^lith^fre- 
root  surfaces  like  the  pile  on  velvet.  These  absorb-  moved.  (After 
ing  root -hairs  never  form  at  the  very  tip  end  of  a  Sachs.) 
new  advancing  root,  and  as,  according  to  Sachs,  they  die  off 
after  a  few  days,  they  form  a  brush -like  covering  on  the  root 
for  a  distance  of  half  an  inch  to  two  or  three  inches,  dying 
off  behind  and  forming  anew  as  the  advance  is  made  into  new 
soil.  In  Fig.  7  are  shown  the  roots  of  two  seedling  white  mus- 
tard plants,  A  with  the  particles  of  soil  still  adhering  to  the 


56 


Irrigation  and   Drainage 


root- hairs  and  held  in  a  body  about  the  young  root,  while  B  is 
intended  to  show  the  appearance  of  the  plant  with  the  soil  grains 
washed  away.  So,  too,  in  Fig.  8  is  shown  the  root  of  wheat  soon 

after  germination,  and  again  four 
weeks  later,  after  the  root  has  ad- 
vanced into  new  soil,  and  the  root- 
hairs  have  died  away  behind  and 
new  ones  formed. 

The  soil  grains  of  a  good  soil 
are  very  small,  the  majority  of 
them  even  much  less  than  TOO  of 
an  inch  in  diameter.  Indeed,  in  a 
heavy  clay  soil  one -half  of  the  dry 
weight  may  be  made  up  of  soil 
grains  as  small  as  25000  of  an  inch 
in  diameter.  Now,  the  fine  root- 
hairs  make  their  way  in  between 
these  minute  soil  grains,  and  even 
change  their  shape  to  fit  them- 
selves Closely  upon  their  surfaces 
in  many  cases. 

The  soil  particles  are  them- 
selves invested  with  a  thin  layer 
of  water,  even  in  the  condition 
which  we  know  as  air-dry,  and 
as  these  minute  root- hairs  apply 
themselves  closely  to  the  surfaces 
of  the  soil  grains,  they  are  brought  into  immediate  contact  with 
the  soil  moisture.  Indeed,  capillarity  has  the  same  tendency  to 
invest  the  root-hairs  with  a  film  of  moisture  that  it  has  the  soil 
grains,  and  we  may  suppose,  in  the  absence  of  direct  observation, 
that  the  root -hairs  all  the  time  carry  a  film  of  moisture  equal  in 
thickness  to  that  which  invests  the  soil  grains  of  like  diameters, 
except  in  so  far  as  the  film  of  water  is  thinned  out  by  the  flow 
through  the  walls  of  the  root-hairs  and  away  through  the  root  to 
meet  the  demands  in  the  green  parts  of  the  plants.  Such  a  thin- 
ning out  of  the  film  of  water  on  the  root -hairs  does  take  place 


B 


Fig.  8.  Root-hairs  of  wheat,— A  when 
very  young,  B  four  weeks  later. 
(After  Sachs.) 


Relation   of  Root -hairs   to    Soil    Grains 


57 


so  long  as  they  are  in  action,  and  it  is  this  very  process  of  thin- 
ning which  furnishes  the  conditions  needed  in  order  to  keep  them 
supplied  with  water  from  the  surfaces  of  the  soil  grains. 

The  effect  of  surface  tension,  as  it  acts  upon  the  water  of  a 
well -drained  soil,  is  to  bring  about  a  certain  regularity  of  dis- 
tribution of  soil  moisture  over  the  surfaces  of  the  soil  grains, 
which  is  determined  by  the  sizes  of  the  grains  and  by  the  dimen- 
sions of  the  open  spaces  between  them.  This  condition  of  things 
may  be  represented  by  what  is  shown  in  Fig.  9  for  a  particular 
soil,  in  which  two  root-hairs  have  found  their  way  in  among  the 
soil  grains. 

To  explain  the  action  of  the  root,  let  us  suppose  that  for 
some  reason  there  has  been  no  movement  of  soil  moisture  and 
no  root  action,  so  that  everything  has  come  to  a  condition  of 
rest,  and  we  have  what  answers  to  the  condition  of  water 
standing  in  a  tank  where  everything  is  still  and  the  surface  has 
become  level.  We  may  now  suppose  that  morning  has  come, 
with  the  sun  shining 
brightly,  so  that  the 
breathing  pores  in 
the  green  parts  oi 
the  plant  have  opened 
wide,  making  it  pos- 
sible for  both  assim  - 
ilation  and  evapora- 
tion to  go  on  rapidly. 
Under  these  "condi- 
tions the  sap  in  the 
tissues  of  the  leaves, 
stem  and  root  will 
gradually  become 
more  dense  than  that 
which  is  contained 
in  the  root-hairs,  which  are  encased  in  the  film  of  soil  mois- 
ture. But  no  sooner  is  this  condition  of  things  established  than 
water  in  the  root -hairs  will  begin  to  move  toward  the  root, 
stem  and  leaves  more  rapidly  than  the  denser  sap  enters  them. 


-I 


Fig.  9.  Distribution  of  water  on  the  surfaces  of  soil 
grains  and  of  root-hairs,  e,  main  root;  1,  air-space; 
2,  soil  grain;  3,  film  of  water;  hh,  root-hairs. 
(After  Sachs.) 


58  Irrigation  and   Drainage 

Just  as  soon  as  this  happens,  however,  the  balance  between 
the  motion  inside  of  the  root-hairs  and  that  outside  of  them  will 
be  destroyed,  and  then  more  water  will  enter  the  root-hair  from 
the  soil  than  has  been  escaping  from  it  into  the  soil  in  a  unit  of 
time.  This  will  thin  out  the  film  of  water  which  surrounds  tba 
root-hairs,  and  then  water  which  has  been  surrounding  the  soil 
grains,  \impelled  by  surface  tension,  must  advance  upon  the  root- 
hairs  to  make  good  that  which  has  been  lost  ;  and  just  so  long 
as  the  water  continues  to  enter  the  roots  from  the  root -hairs 
faster  than  osmotic  pressure  can  restore  it,  just  so  long  will 
surface  tension  force  the  water  from  the  soil  grains  upon  the 
walls  of  the  root -hairs. 

Not  only  will  the  water  which  surrounds  the  soil  grains  move 
toward  and  upon  the  root-hairs  so  long  as  evaporation  is  going  on 
from  the  plant  and  assimilation  is  taking  place  in  its  cells,  but 
with  it  will  go  the  salts  containing  potash,  nitrogen,  phosphorus, 
and  other  ash  ingredients  of  plants,  which  have  been  dissolved 
by  the  moisture  surrounding  the  grains. 

In  the  figure  the  root-hair,  h,  h,  leading  out  from  the  main 
root,  e,  is  represented,  for  the  sake  of  clearness,  nearly  full  width 
throughout  its  course,  and,  as  if  it  had  either  found  or  had  made 
for  itself,  by  setting  the  soil  grains  aside,  an  unobstructed  path 
in  which  to  develop.  As  a  matter  of  fact,  these  root-hairs  are 
obliged  to  work  their  way  as  best  they  can  between  the  angles 
formed  by  the  meeting  of  the  soil  grains,  changing  both  their 
direction  and  their  form  in  order  to  do  so,  and  sometimes  the 
spaces  are  so  narrow  or  the  turns  so  abrupt  that  the  root-hair 
seems  to  have  applied  itself  to  the  soil,  and  to  have  adapted  its 
shape  so  as  to  more  completely  come  in  contact  with  the  surface 
of  the  grain  itself. 

As  the  water  surrounding  the  soil  grains,  and  which  is  also 
drawn  out  upon  the  root-hairs,  becomes  more  and  more  ex- 
hausted, the  film  finally  becomes  so  thin  that  the  rate  at  which 
the  water  can  be  moved  out  upon  the  root-hairs  is  so  slow  that  it 
is  no  longer  able  to  meet  the  needs  of  the  plant,  and  it  wilts, 
and  finally  ceases  to  grow  altogether. 

Attention  should   be  called   to  the  fact  that   fresh   growing 


The   Extent   of  Root   Surface  59 

roots  usually  have  an  acid  reaction,  and  so  much  so  that  if  they 
are  allowed  to  develop  in  contact  with  blue  litmus  paper,  it  is 
changed  to  red  along  the  lines  of  contact  with  the  root.  Further 
than  this,  if  the  roots  of  a  plant  are  allowed  to  develop  in  con- 
tact with  a  polished  surface  of  marble,  the  lines  of  root  contact 
with  it  will  be  plainly  etched  into  its  surface.  Such  observations 
as  these  lead  to  the  belief  that  the  delicate  root-hairs,  at  their 
innumerable  places  of  contact,  hasten  the  solution  of  plant- food 
from  the  difficultly  soluble  ingredients  of  the  soil  by  the  acids 
which  permeate  their  walls  being  exuded  upon  the  soil  grains, 
and  there,  in  conjunction  with  the  water,  being  able  to  dissolve 
materials  much  more  rapidly  than  water  alone  could  do. 

When  we  reflect  upon  the  many  wide  leaves  with  which  most 
land  plants  are  provided,  we  are  impressed  with  the  great  extent 
of  surface  through  which  the  sunshine  and  the  air  may  come  into 
touch  with  the  plant.  But  broad  as  these  leaf  surfaces  are,  they 
only  in  the  smallest  way  express  the  real  magnitude  of  the  sur- 
face of  contact,  for  the  air  actually  enters  the  leaf  and  passes 
around  and  between  and  in  contact  with  the  millions  of  loosely 
packed  cells  in  every  leaf,  and  the  number  of  times  the  extent  of 
the  internal  surface  of  the  leaf  exceeds  that  of  its  outer  sur- 
face is  more  than  one  would  dare  to  express.  Then,  too,  to  in- 
crease the  contact  surface  for  sunlight,  the  chlorophyll  grains 
which  are  scattered  through  the  interior  of  the  cells  around 
which  the  air  can  pass  provide  an  enormous  surface  for  the 
absorption  of  light. 

In  the  root  system  under  ground,  the  extremely  numerous 
root-hairs,  small  as  they  are,  yet  provide  a  surface  for  the  con- 
tact of  soil  and  moisture  with  the  plant  which  is  quite  commeD- 
surate  with  that  furnished  by  the  leaf. 

That  we  may  the  more  clearly  appreciate  the  great  need 
there  is  for  the  vast  extent  of  root  surface  spread  out  by  agri- 
cultural crops,  and  how  important  it  is  that  there  shall  be  a 
deep,  well-drained  soil  in  which  the  roots  may  expand,  let  me 
give  the  measured  amounts  of  water  used  by  four  stalks  of  corn, 
and  withdrawn  by  their  roots  from  the  soil,  between  July  29  and 
August  11.  Two  of  the  maize  plants  were  growing  in  each  of 


60 


Irrigation  and   Drainage 


two  cylinders  filled  with  soil,  having  a  depth  of  42  inches  and  a 
diameter  of  18  inches.  These  four  stalks  of  corn,  as  they  were 
coming  into  tassel  and  their  ears  were  beginning  to  form,  used 
during  13  days  150.6  pounds  of  water,  or  at  the  mean  rate  daily 
of  2.896  pounds  for  each  stalk.  Had  an  acre  of  ground  been 
planted  to  corn  in  rows  3  feet  8  inches  each  way  and  four  stalks 
in  a  hill,  then,  with  an  average  consumption  of  water  at  the  ob- 


Fig.  10.    Total  root  of  four  stalks  of  maize,  and  of  oats,  clover  and  barley. 
(From  "The  Soil.") 

served  rate  given  above,  there  would  have  been  withdrawn  from 
that  acre  an  amount  of  water,  during  those  13  days,  equal  to  244 
tons,  or  2.42  acre-inches  ;  and  when  it  is  observed  that  this  water 
was  withdrawn  from  a  soil  so  dry  that  no  amount  of  pressure 
could  express  a  drop  of  water  from  it,  it  is  not  strange  that  such 
a  mass  of  roots  as  those  shown  in  Fig.  10  should  be  required  to 
carry  away  from  the  soil  the  water  absorbed  by  the  root -hairs  as 


The   Extent   of  Root   Surface  61 

rapidly  as  it  was  needed.  In  reflecting  upon  the  extent  of  root, 
surface  indicated  by  the  photo -engraving,  let  it  be  remembered 
that  no  root-hairs  contribute  to  the  mass  of  the  bundle,  and  that 
only  a  part  of  the  roots  proper  are  there,  for  many  of  the  smaller 
fibers  were  unavoidably  broken  off  during  the  operation  of  wash- 
ing away  the  soil. 

Referring,  now,  to  Fig.  11,  it  will  be  seen  how  completely  the 


Fig.  11.    Distribution  of  corn  roots  in  field  soil.     (From  "The  Soil.") 

whole  soil  of  the  field  is  threaded  with  roots  ;  for  in  both  casei> 
two  hills  of  corn,  standing  opposite  each  other  in  adjacent  rows, 
are  shown,  and  the  roots  meet  and  pass  one  another  between  the 
hills,  and  in  the  younger  stage  these  had  already  exceeded  a 
depth  of  two  feet  ;  while  in  the  second  case,  taken  just  as  the 
corn  was  coming  into  tassel,  the  roots  had  descended  until  at 
this  time  the  whole  upper  three  feet  of  the  field  soil  was  so  fully 


62  Irrigation  and   Drainage 

occupied  with  corn  roots  that  not  a  cube  of  earth  one  inch  on  a 
side  existed  in  the  three  feet  of  depth  which  was  not  penetrated 
by  more  than  one  fiber  of  threadlike  size.  In  many  parts  of 
the  soil  the  roots  were  much  closer  together  than  this. 

At  the  distance  apart  of  planting  in  the  field  from  which  these 
roots  were  taken,  there  were,  in  the  surface  three  feet,  40%  cubic 
feet  of  soil  available  for  each  four  stalks,  so  that  by  multiplying 
the  1,723  cubic  inches  in  one  cubic  foot  by  40%,  the  number  of 
cubic  feet  of  soil  occupied,  we  get  a  total  of  69,696  cubic  inches. 
If,  then,  each  cubic  inch  of  this  soil  contained  not  less  than  one 
linear  inch  of  thread-like  root,  their  aggregate  length  could  not 
be  less  than  one-twelfth  of  69,696,  or  5,808  feet,  which  is  1.1 
miles.  But  this  extent  of  root -surf  ace  does  not  even  express  the 
amount  of  that  to  which  the  root-hairs,  which  are  the  real  absorb- 
ing surfaces,  are  attached  ;  and  hence  we  must  understand  that 
the  actual  area  of  surface  of  root -hairs  for  a  full-grown  hill  of 
corn  is  very  much  greater  than  would  be  indicated  by  the  figures 
given  above.' 

Let  the  reader  bear  in  mind  that  the  corn  roots  here  under 
consideration  grew  in  the  field  under  perfectly  natural  conditions, 
and  that  the  cage  of  wire  shown  in  the  engraving  was  simply 
slipped  over  the  block  of  soil  which  contained  the  roots  there 
shown,  after  the  corn  had  reached  that  stage  of  maturity. 
It  should  also  be  understood  that  the  four  stalks  of  corn  which 
absorbed  from  the  soil  the  150.6  pounds  of  water  in  13  days  did 
it  at  the  stage  of  growth  represented  by  the  oldest  plants  in 
Fig.  11;  and  further,  that  these  were  only  good  average  plants, 
such  as  would  make  a  yield  of  4.5  tons  of  dry  matter  per  acre. 

It  may  be  difficult  for  some  persons  to  realize  how  it  is 
possible  for  the  delicate  roots  of  plants  to  force  their  way 
through  the  soil  to  depths  such  as  are  indicated  by  the  engrav- 
ings above,  especially  when  the  subsoil  is  a  stiff,  heavy  clay,  as 
it  -was  in  this  case.  Nature's  method  of.  overcoming  the  diffi- 
culty, however,  is  simple  enough  when  we  come  to  understand  it, 
and  it  is  as  effective  as  it  is  simple. 

The  first  fact  which  we  need  to  understand  when  we  wish  to 
learn  how  a  root  advances  through  the  soil,  is  that  the  soil  grains 


How    Roots   Advance   in    Soil  68 

in  the  upper  four  to  six  feet  are  never  everywhere  in  close  con- 
tact with  one  another.  There  are  great  numbers  of  empty  spaces 
all  through  the  surface  layers  of  earth,  and  we  get  a  very  forcible 
illustration  of  this  fact  in  setting  fence  posts.  Here  we  dig  a 
moderate  sized  post  hole,  2  or  2%"  feet  deep,  place  a  6 -inch  post  in 
the  hole,  and  then  scrape  and  ram  into  the  same  hole  all  of  the 
dirt  which  was  removed  from  it,  and  if  the  job  is  well  done  we 
have  a  scant  supply  to  fill  it.  It  is  the  existence  of  these  unoccu- 
pied cavities  in  the  soil  which  enables  roots  to  make  their  way 
through  it  by  wedging  it  aside.  In  a  thoroughly  puddled  soil  it 
is  impossible  for  roots  to  develop,  not  simply  for  lack  of  air,  but 
because  there  is  no  room  into  which  it  is  possible  to  set  the  soil 
aside  to  make  place  for  the  root.  When  a  fine-grained  soil  is 
thoroughly  puddled,  all  of  the  small  clusters  of  grains  which  in  a 
soil  in  good  tilth  hold  together,  are  completely  broken  down,  and 
the  smallest  particles  are  packed  in  between  the  larger  ones  until 
its  cavities  are  so  completely  obliterated  that  even  water  will 
not  penetrate  it  ;  and  when  this  is  true  there  is  not  even  room  for 
the  root-hairs  to  make  their  way  between  the  angles  formed  by 
the  soil-grains,  for  the  finest  silt  and  clay  particles  have  been 
forced  into  these  to  fill  them  up. 

The  second  fact  needed  to  understand  how  the  root  advances 
itself  in  the  soil  is,  that  it  makes  use  of  osmotic  pressure  to  set 
the  soil  grains  aside.  Most  of  us  know  with  what  force  dry  wood 
will  expand  when  it  becomes  wet  and  is  allowed  to  swell.  Iron 
hoops  are  burst  by  the  pressure  developed.  A  primitive  method 
of  blasting  rock  was  to  drive  diy  blocks  of  wood  into  the  holes 
and  then  wet  them.  Another  method  of  blasting  is  to  fill  the 
drill  holes  with  unslaked  lime  and  then  add  water  to  slake  it.  In 
all  of  these  cases,  the  work  is  done  by  osmotic  pressure,  and 
the  results  illustrate  how  very  great  this  force  is  when  it  is 
restrained,  and  how  thoroughly  adequate  it  would  be  for  the  pur- 
poses of  the  root  in  setting  aside  the  soil  particles  if  it  could  make 
use  of  it. 

The  method  by  which  the  root  uses  osmotic  pressure  in  mak- 
ing its  way  through  the  soil  may  be  explained  with  the  aid  of 
Fig.  12,  which  represents  diagrammatically  the  tip  of  an  advancing 


64 


Irrigation  and   Drainage 


root  in  the  soil.  It  has  been  found  that  a  short  way  back  from  the 
tip  end  of  a  growing  root,  there  is  at  1  a  center  of  growth,  where 
new  cells  are  developed  by  repeated  enlargements  and  divisions. 
On  the  forward  or  advancing  side  of  this  center  the  new  cells 
form  the  root-cap,  which  in  the  figure  is  represented  by  the  cells 

with  heavier  lines  ;  while 
those  forming  on  the  rear 
side  of  the  center  are  fin- 
ally transformed  into  the 
various  structures  which 
constitute  the  body  of  the 
root  proper. 

The  root -cap  is  a  sort 
of  shield  or  thimble,  under 
the  protection  of  which  the 
root  advances  to  set  aside 
the    soil    grains,    and    the 
method  of  advance  is  this  : 
At  the  center  of  growth, 
new  cells  are  forming  and 
Fig.  12.    Method  by  which  root-hairs  advance    enlarging    out    of    the    as- 
through  the  soil.     (Adapted  from  Sachs.)        similated    products     which 

are    being    brought     down 

from  the  geeen  parts  of  the  plants  by  osmotic  pressure.  But 
when  this  strong  pressure  drives  the  sap  into  the  forming  cells, 
they  must  enlarge  just  as  the  dry  wood  swells,  and  in  doing  so 
something  must  give  way.  As  the  body  of  the  root  is  larger  than 
the  tip,  and  as  it  is  already  anchored  to  the  soil  by  the  root-hairs 
and  any  branches  which  may  have  formed,  the  direction  of  least 
resistance  is  forward,  and  the  cells  which  are  in  the  interior  of 
the  base  of  the  root-cap  are  crowded  forward  and  the  wal-ls  of  the 
cap  are  wedged  outward  so  that  the  soil  grains  on  all  sides  are 
displaced,  making  room  for  the  end  of  the  root  proper  to  be  built 
into  it.  The  root-cap  does  not  slide  forward  through  the  soil, 
shoving  past  the  soil  grains,  but  its  outer  and  rear  cells  hold 
firmly  against  the  earth  as  the  root  builds  past  them,  and  as  fast 
as  they  have  performed  their  function  they  die  and  new  ones  are 


How   Roots   Advance   in    Soil  65 

formed  in  advance.  The  root-cap,  then,  is  a  sort  of  point 
through  which  the  root  advances,  and  which  is  being  continually 
replaced  by  a  new  growth. 

The  increase  of  the  root  in  diameter  throughout  its  length  is 
produced  by  the  addition  of  new  cells  wholly  within  those  which 
lie  in  contact  with  the  soil,  and  the  same  osmotic  pressure  is  the 
power  which  is  exerted  outward  on  all  sides  to  move  the  earth 
away  and  give  room  for  the  increase  in  size. 

Since  this  osmotic  pressure  in  the  roots  of  plants  may  be  very 
great,  certainly  more  than  100  pounds  to  the  square  inch,  and 
presumably  several  times  this  amount,  and  since  during  the 
growth  of  the  root  the  pressure  is  increased  slowly,  and  acts 
gradually  to  set  the  soil  aside,  it  is  not  difficult  to  see  that  the 
plant  has  chosen  a  method  of  making  its  way  through  the  soil 
which  is  not  only  effective,  but  one  which  utilizes  the  energy  and 
the  materials  present  in  a  soil  during  the  growing  season  with 
which  to  accomplish  its  purpose.  The  molecules  of  soil  moisture 
are  at  once  the  hammer  and  the  wedge,  which  are  driven  by  soil 
temperature  into  the  growing  cells  to  expand  them  and  set  the 
soil  aside. 


PART  I 
IRRIGATION   CULTURE 

CHAPTER   I 

THE    EXTENT    AND    GEOGRAPHIC    RANGE    OF 
IRRIGATION 

WHILE  there  is  no  reason  to  suppose  that  the  rais- 
ing of  crops  by  irrigation  on  an  extended  scale  is  as 
old  as  agriculture  itself,  the  methods  have,  nevertheless, 
been  so  long  practiced  as  to  far  antedate  authentic  his- 
tory. We  are  told  that  "the  numerous  remains  of 
huge  tanks,  dams,  canals,  aqueducts,  pipes  and  pumps 
in  Egypt,  Assyria,  Mesopotamia,  India,  Ceylon,  Phoe- 
nicia, and  Italy,  prove  that  the  ancients  had  a  far 
more  perfect  knowledge  of  hydraulic  science  than  most 
people  are  inclined  to  credit  them  with." 

In  a  paper  read  before  the  Royal  Society  of  New 
South  Wales  in  1887,  Mr.  Frederick  S.  Gipps  states 
that  the  first  artificial  lake  or  reservoir  of  which  we 
have  authentic  record  was  Lake  Maeris,  constructed, 
some  historians  affirm,  by  King  Maeris,  and  others  by 
King  Amenemhet  III,  in  the  twelfth  dynasty,  2084 
B.  C.  Its  object,  it  is  thought,  was  the  regulation  of 

(66) 


Antiquity  of  Irrigation  67 

the  inundations  of  the  Nile,  with  which  it  communi- 
cated through  a  canal  12  miles  long  and  50  feet  broad. 
When  the  river  rose  to  a  height  of  24  feet,  and  was 
likely  to  be  disastrous  to  crops,  the  sluices  were  opened 
and  the  river  relieved  by  sending  the  flood  into  this 
lake,  which  modern  travelers  give  a  circumference  of 
50  miles  ;  but  at  times  of  low  water,  when  drought 
was  threatened,  the  gates  could  be  opened  and  the 
volume  of  the  stream  reinforced  by  the  water  stored 
in  this  reservoir. 

Sesostris,  who  reigned  in  Egypt  in  1491  B.  C.,  is 
said  to  have  had  a  great  number  of  canals  cut  for  the 
purposes  of  trade  and  irrigation,  and  to  have  designed 
the  first  canal  to  connect  the  Bed  Sea  with  the  Medi- 
terranean, which  was  continued  by  Darius  but  aban- 
doned by  him,  and  ultimately  completed  under  the 
Ptolemies.  So  numerous  are  the  irrigation  canals  of 
Egypt  that  it  is  estimated  that  not  more  than  one- 
tenth  of  the  water  which  enters  Egypt  by  the  Nile 
finds  its  way  into  the  Mediterranean  Sea.  Fig.  13 
shows  Lower  Egypt,  with  its  extended  system  of  canals 
as  they  exist  to-day. 

The  Assyrians  appear  to  have  been  equally  re- 
nowned with  the  Egyptians,  from  very  ancient  times, 
for  their  skill  and  ingenuity  in  developing  extended 
irrigation  systems,  which  converted  the  naturally  ster- 
ile valleys  of  the  Euphrates  and  Tigris  into  the  most 
fertile  of  fields.  We  are  told  that  the  country  below 
Hit,  on  the  Euphrates,  and  Samarra,  on  the  Tigris, 
was  at  one  time  intersected  with  numerous  canals,  one 
of  the  most  ancient  of  which  was  the  Nahr  Malikah, 


68 


Irrigation  and   Drainage 


connecting  the  Euphrates  with  the  Tigris.  The  an- 
cient city  of  Babylon  seems  to  have  been  protected 
from  the  floods  of  June,  July  and  August  by  high 


CAVJkU 

•JJBMN.K.J  CUT. 


Fig.  13.    Egyptian  system  of  irrigation  canals  at  the  present  time.    (Willcocks.) 

cemented  brick  embankments  on  both  banks  of  the 
Euphrates,  and,  to  supplement  the  protection  of  these, 
and  to  store  water  for  irrigation,  a  large  reservoir  was 
excavated  42  miles  in  circumference  and  35  feet  deep, 
into  which  the  whole  river  might  be  turned  through 
an  artificial  canal.  There  were  five  principal  canals 
supplied  by  the  Euphrates  —  the  Nahr  Malikah,  the 
Nah-raga,  the  Nahr  Sares,  the  Kutha,  and  the  Palla- 
copus  ;  while  -the  Tigris  furnished  water  for  the  great 


Antiquity  of  Irrigation  69 

Nahrawan  and  Dyiel,  besides  several  smaller  ones. 
Along  the  banks  of  the  former  of  these  canals  fed  by 
the  Tigris  are  now  found  the  ruins  of  numerous  towns 
and  cities  on  both  sides,  which  are  silent  witnesses  of 
the  great  importance  it  held,  and  the  great  antiquity 
of  the  work.  It  started  on  the  right  bank  of  the  river, 
where  it  comes  from  the  Hamrine  Hills,  and  was  led 
away  at  a  distance  of  six  or  seven  miles  from  the 
stream  toward  Samarra,  where  it  joined  a  second 
canal.  Another  feeder  was  received  10  miles  farther 
on  its  course  to  Bagdad,  a  few  miles  beyond  which  its 
waters  fell  into  the  river  Shirwan,  and  were  again 
taken  out  over  a  wier  and  led  on  through  Kurzistan. 
It  absorbed  all  the  streams  from  the  Sour  and  Buck- 
haree  Mountains,  and  finally  discharged  into  Kerkha  • 
River,  but  only  after  having  attained  a  length  exceed- 
ing 400  miles,  with  a  width  varying  from  250  to  400 
feet.  This  great  canal,  with  its  numerous  branches  on 
either  side,  leading  water  to  broad  irrigated  fields, 
while  it  bore  along  its  main  waterway  the  commerce 
of  those  far  distant  days,  stands  out  as  a  piece  of  bold 
engineering  hardly  equaled  by  anything  of  its  kind  in 
modern  times. 

The  Pho3nicians,  in  the  time  of  their  zenith,  were 
celebrated  for  their  canals,  used  both  for  irrigation 
and  city  purposes  ;  and  at  the  time  of  the  invasion  of 
Africa  the  Syracusan  General  Agathocles  wrote  that 
"the  African  shore  was  covered  with  gardens  and  large 
plantations  everywhere  abounding  in  canals,  by  means 
of  which  they  were  plentif ully  watered  ; "  and  50  years 
later,  when  the  Romans  invaded  the  Carthaginian  do- 


70  Irrigation  and   Drainage 

minions,  their  historian,  Polybius,  drew  a  similar  pic- 
ture of  the  high  state  of  cultivation  of  this  country. 

In  the  early  days  of  both  Grecian  and  Roman  his- 
tory, great  progress  had  already  been  made  by  these 
peoples  in  handling  and  conveying  water  by  gravity 
over  long  distances  for  domestic  purposes.  At  Patara 
the  Greeks,  according  to  Herodotus,  carried  an  aque- 
duct across  a  ravine  200  feet  wide  and  250  feet  deep, 
constructing  a  pipe  line  by  drilling  13 -inch  holes 
through  cubic  blocks  3  feet  in  diameter,  fitting  these 
blocks  together  with  curved  necks  and  recesses,  whose 
joints  were  laid  in  cement  and  held  secure  by  means 
of  iron  bands  run  with  lead.  This  was  an  inverted 
syphon,  now  so  often  used  to  cross  a  ravine  or  canon 
in  the  west,  but  made  from  stone  instead  of  steel 
or  redwood  hooped  with  steel,  so  commonly  used  to- 
day. 

Rome  was  supplied  with  water  in  Nero's  time  by 
nine  separate  aqueducts  aggregating  a  length  of  255 
miles,  and  which  delivered  daily  173,000,000  gallons 
of  water,  which  was  later  increased  to  312,500,000  gal- 
lons. The  Aqua  Martia  conduit,  which  brought  the 
drinking  water  for  the  city,  had  a  diameter  of  16  feet, 
and  was  40  miles  long. 

When  the  Romans  invaded  France,  they  constructed 
great  systems  of  water  works  for  cities  in  various 
places  —  at  Lyons,  Souy,  Nismes,  Frejus,  and  Metz. 
The  Nismes  conduit  was  constructed  at  the  time  of 
Augustus,  19  B.C.,  and  delivered  14,000,000  gallons 
per  day.  It  is  noted  for  the  great  Pont  du  Gard, 
which  carried  it  across  a  ravine,  and  which  is  spoken 


Antiquity  of  Irrigation  71 

of  by  Humble  as  one  of  the  grandest  monuments  the 
Romans  left  in  France. 

China,  like  Egypt,  dates  its  early  enterprises  of  irri- 
gation and  transportation  by  water  far  back  in  antiq- 
uity, for  she  has  numerous  canals,  some  of  them 
the  most  stupendous  works  of  the  kind  ever  under- 
taken. The  Great  Imperial  Canal  has  a  length  of  650 
miles,  and  connects  the  Hoang-Ho  with  the  Yang-tse- 
Kiang.  It  lias  a  depth  seldom  exceeding  5  to  6  feet, 
and  in  it  the  water  moves  at  the  rate  of  2%  miles  per 
hour.  In  its  path  there  are  several  large  lakes,  and 
across  these  the  canal  is  carried  on  the  crest  of  enor- 
mous dykes. 

If  we  leave  the  Old  World  and  come  to  the  New  for 
records  of  an  early  development  of  the  cultivation  of 
land  by  irrigation,  we  shall  not  be  disappointed,  for 
traces  of  an  early  civilization  in  Colorado,  New  Mexico 
and  Arizona,  and  extending  through  Mexico  and  Cen- 
tral America  on  into  Peru,  are  found  in  the  ruins  of 
ancient  towns  and  irrigating  canals  in  many  places. 
When  the  Spaniards  invaded  Mexico,  Central  America 
and  Peru,  they  were  greatly  surprised  to  find  in  these 
countries,  and  particularly  in  Peru,  the  land  of  the 
Incas,  very  elaborate  and  extensive  irrigation  systems, 
laid  out  and  in  actual  general  use  by  these  people. 

Prescott,  in  his  "Conquest  of  Peru,"  speaking  of 
the  use  of  water  for  irrigation,  writes  that  water  "was 
conveyed  by  means  of  canals  and  subterraneous  aque- 
ducts executed  on  a  noble  scale.  They  consisted  of 
large  slabs  of  freestone  nicely  fitted  together  without 
cement,  and  discharged  a  volume  of  water  sufficient, 


72  Irrigation  and   Drainage 

by  means  of  latent  ducts  or  sluices,  to  moisten  the 
lands  in  the  lower  levels  through  which  they  passed. 
Some  of  these  aqueducts  were  of  great  length.  One, 
that  traversed  the  district  of  Condesuyos,  measured 
between  400  and  500  miles.  They  were  brought  from 
some  lake  or  natural  reservoir  in  the  heart  of  the 
mountains,  and  were  fed  at  intervals  by  other  basins 
which  lay  in  their  route  along  the  slopes  of  the  Sierra. 
In  their  descent  a  passage  was  sometimes  opened 
through  rocks,  and  this  without  the  aid  of  iron  tools  ; 
impracticable  mountains  were  to  be  turned,  rivers  and 
marshes  to  be  crossed  —  in  short,  the  same  obstacles 
were  to  be  encountered  as  in  the  construction  of  their 
mighty  roads." 

THE     EXTENT     OF     IRRIGATION 

From  what  has  been  said  regarding  the  antiquity  of  irriga- 
tion, we  shall  not  be  surprised  to  find  that  its  practice  has  found 
a  geographic  range  which  is  commensurate  with  its  distribution 
in  time.  We  look  first  to  European  countries,  and  begin  with 
Italy,  where  irrigation  certainly  had  a  very  early  development, 
and  has  ever  since  been  yearly  practiced  in  rural  life. 

In  the  valley  of  the  Po,  naturally  very  fertile,  but  made  more 
so  by  thorough  and  systematic  irrigation,  water  is  extensively 
applied  to  almost  all  crops.  To  convey  some  idea  of  the  general 
practice  of  irrigation  in  the  Po  valley,  it  may  be  stated  that  on 
August  7,  1895,  while  riding  by  rail  from  Turin  to  Milan,  between 
Chivasso  and  Santhia,  a  distance  of  18.5  miles,  the  writer  saw 
water  being  applied  to  100  different  fields  of  maize  by  as  many 
different  parties,  and  the  fields  ranged  in  size  all  the  way  from  4 
to  20  acres.  Wheat,  barley,  hemp,  rye-grass,  clover,  rice,  and 
maize  are  among  the  field  crops  generally  and  extensively  irri- 
gated in  this,  part  of  Italy.  So,  too,  very  extensive  mulberry 


Extent  of  Irrigation  73 

orchards  are  grown  for  the  feeding  of  silk  worms,  and  these  are 
set  along  the  main  and  distributing  canals,  while  the  space  be- 
tween them  is  occupied  by  various  kinds  of  farm  crops. 

In  Sicily  and  throughout  southern  Italy,  nearly  all  fruit  cul- 
ture is  carried  on  by  irrigation,  the  ratio  of  irrigated  to  non- 
irrigated  orchards  being  as  15  to  1,  and  it  is  said  that  100  10 -year- 
old  lemon  trees,  when  ,  irrigated,  have  yielded,  on  the  average, 
15,000  lemons,  while  similar  orchards  under  similar  conditions, 
but  riot  watered,  yield,  on  the  average,  but  10,000,  or  one-third 
less  per  annum.  In  Lombardy,  there  were  under  irrigation,  in 
1878,  2,034,000  acres;  in  Piedmont,  1,329,000  acres;  in  Venetia, 
Emilia,  and  other  provinces,  enough  to  make  a  total  of  4,715,000 
acres. 

In  Spain,  irrigation  is  widely  practiced,  and  has  been  at  least 
since  Roman  and  Moorish  times,  and  the  total  acreage  has  been 
variously  estimated  at  from  700,000  to  6,000,000,  the  first  figure 
referring  to  cereals,  vegetables  and  fruits,  and  the  latter  to  forage 
plants  and  grass  lands  also.  In  the  last  edition  of  the  Encyclo- 
pedia Britannica,  the  area  under  irrigation  is  placed  at  2,840,- 
160  acres. 

In  France,  irrigation  began  at  an  early  date,  and  in  recent 
years  new  interest  has  been  taken  in  the  subject,  so  much  so  that 
in  Consul-General  Rathbone's  "Report  on  Canals  and  Irrigation, 
1891,"  it  is  stated  that  during  the  past  ten  years  in  the  Depart- 
ments Drome,  Alpes  Maritimes,  Aude  and  Herault,  Vaucluse, 
Basses- Alpes,  Hautes- Alpes,  and  Loire,  41,460,000  francs  were 
expended  on  no  less  than  13  different  canals  for  waterways  and 
irrigation. 

The  Forez  Canal,* supplied  by  the  Loire  River,  and  irrigating, 
it  is  said,  65,000  acres,  was  begun  in  1863,  and  the  national  gov- 
ernment granted  $122,200  for  it,  loaning  the  balance  needed  to  the 
department  at  4  per  cent.  In  1886  there  were  23,000  acres  served 
with  115  miles  of  ditches,  at  a  cost  of  $9.50  per  acre.  The  water 
is  distributed  periodically,  through  pipes  carrying  it  to  points 
most  convenient  for  a  group  of  farms,  where  it  is  delivered  to  the 

*  "  Report  on  Irrigation,"  to  Senate.    Ex.  Doc.  41,  Part  1, 1892. 


74 


Irrigation  and   Drainage 


farm  laterals.  The  water  is  served  once  each  week,  on  the  same 
day  and  hour,  the  amount  received  being  regulated  by  the  amount 
purchased.  The  delivery  commences  on  land  farthest  from  the 
main  canal,  and  each  proprietor  turns  off  the  water  from  his  lat- 
eral when  he  has  received  the  amount  paid  for,  and  the  next  in 
order  is  then  served.  The  assessment  is  made  out  by  November 
1,  and  each  irrigator  is  notified  of  the  days  and  hours  when  water 
will  be  applied  to  his  land.  This  irrigation  is  used  almost  wholly 
on  meadows,  and  it  is  stated  that  the  value  of  land  has  increased 


Fig.  14.    Alpine  water-meadows  on  the  south  side  of  the 
Simplon  Pass,  Switzerland. 

from  $44  to  $300  per  acre  since  the  development  of  the  irrigation 
facilities. 

In  Switzerland,  the  mountain  streams  and  rills  are  used  in 
very  many  places  on  meadows,  and  this  has  been  done  so  long  and 
continuously  on  some  meadows  that  very  decided  ridges  have  been 
formed  from  the  sediment  moved  by  the  water ;  and  we  were  sur- 
prised to  find  that,  even  so  high  up  as  the  south  side  of  the  Sim- 
plon Pass,  meadows  are  regularly  irrigated,  even  by  the  waters 


Irrigation  in   Europe  75 

which  have  come  down  from  the  perennial  snow  fields  of  still 
higher  altitudes,  as  shown  in  Fig.  14. 

In  Belgium  there  is  a  network  of  canals  known  as  de  la  Cam- 
pine,  which  have  an  aggregate  length  of  350  miles,  constructed 
both  for  navigation  and  irrigation  purposes,  at  a  cost  placed  at 
$5,000,000.  This  water  is  generally  used  in  the  irrigation  of 
meadow  lands,  and  the  soil  of  the  section  is  very  sandy.  It  is 
even  said  to  have  been  wholly  unproductive  until  it  was  reclaimed 
by  irrigation. 

The  figures  given  by  E.  Laveleye  will  show  the  effect  of  irri- 
gation on  this  land.  An  area 'of  5,636  acres  of  barren  soil,  pro- 
ducing absolutely  nothing  before  irrigation,  now  yields  an  average 
of  1.32  tons  of  hay  per  acre  for  the  first  crop,  and  the  aftermath 
is  counted  worth  a  third  as  much,  making  the  total  equivalent  to  a 
crop  of  1.76  tons  per  acre. 

In  Denmark,  too,  an  extensive  system  of  145  canals,  carrying, 
in  1890,  22,000  second-feet  of  water,  has  been  provided,  whose 
object  is  to  reclaim  some  of  the  sandy  heath  lands  in  Jutland  : 
and  it  is  said  that  the  21,000  acres  of  land  which  has  been 
brought  under  cultivation  has  increased  in  value  at  the  rate  of 
nearly  $80  per  acre. 

In  Austria-Hungary,  irrigation,  largely  meadow,  is  practiced 
in  the  Mattig  valley,  in  upper  Austria  ;  in  lower  Austria  ;  near 
Klagenfurth,  in  Carinthia  ;  in  certain  of  the  upper  and  central 
valleys  in  Tyrol  ;  in  the  Bistritz  valley,  and  in  the  valley  of  the 
Elbe,  in  Bohemia.  In  these  countries  the  water  is  usually  taken 
from  rivers,  creeks,  springs,  and  ponds,  or  reservoirs  constructed 
to  impound  that  which  is  running  to  waste,  and  is  led  directly 
upon  the  land  by  gravity,  being  taken  from  the  natural  channels 
by  damming  the  stream  until  head  enough  has  been  secured  to 
cause  the  water  to  discharge  into  the  distributing  canal  or  ditch. 

For  the  irrigation  of  small  meadows,  water  wheels  are  found 
along  the  streams  in  many  places,  for  lifting  the  water  out  of  the 
channels  where  it  runs  too  low  to  be  led  out  in  the  usual  manner. 
These  wheels,  provided  with  buckets,  according  to  Consul-General 
Goldschmidt,  are  found  in  great  numbers  on  the  Eisack  Kiver,  in 
Tyrol,  above  Bozeii.  About  the  large  cities,  small  gardens  are 


76 


Irrigation  and   Drainage 


irrigated  by  pumps,  worked  usually  by  horse-power,  taking  water 
from  wells  or  cisterns.  In  the  mountainous  portions  of  the  Tyrol, 
meadow  irrigation  is  said  to  be  both  very  extensive  and  very 
ancient,  and  in  recent  times  many  of  the  old  works  have  been 
reconstructed  and  new  ones  introduced. 

So,   too,    in   parts  of  Bavaria,  meadow  irrigation  is  common, 
and  at  Baiersdorf,  on   the   river  Regnitz,,  the  writer   counted,  in 


Fig.  15.    Wheel  for  lifting  water,  at  Baiersdorf,  Bavaria. 

1895,  no  less  than  20  of  the  wheels  represented  in  Fig.  15  in  a 
distance  of  1%  miles,  all  of  them  used  in  lifting  water  for  meadow 
irrigation,  the  grass  being  cut  and  fed  to  the  cows  green. 

Even  in  England,  there  are  numerous  water-meadows  which 
have  been  irrigated  so  long  that  the  time  at  which  they  were  laid 
out,  and  the  canals  and  ditches  dug,  is  unknown.  It  is  thought 
that  some  of  the  English  water-meadows  were  constructed  undev 
the  direction  of  Roman  engineering  skill,  while  others  have  sup- 


Irrigation  in    Europe  77 

posed  that  they  were  introduced  from  the  Netherlands;  but  the 
fact  that  the  character  of  the  works  bears  a  much  closer  resem- 
blance to  the  Italian  construction,  and  that  extensive  tracts  of 
irrigated  land  are  found  in  the  vicinity  of  ancient  Roman  stations, 
as  at  Cirencester,  lends  support  to  the  former  view. 

•This  water-meadow  irrigation  of  England  is  largely  confined 
to  the  southern  parts  of  the  island,  as  in  Berkshire,  along  the 
Kennet  ;  in  Derbyshire,  in  the  valley  of  the  Dove  ;  in  Dorset  ;  in 
Gloucestershire,  along  the  Churn,  Severn,  Avon,  Lidden,  and  other 
streams  ;  on  the  Avon,  Itchen,  and  Test,  in  Hampshire  ;  in  Wilt- 
shire ;  in  Worcestershire  and  in  Devonshire,  where  catch  meadows 


Fig.  16.     River  and  canal  for  water-meadow  irrigation,  at  Salisbury,  England. 

are  laid  out  in  the  valleys  of  many  rivers  and  brooks.  In  Figs. 
16  and  17  are  shown  two  views  of  water-meadow  construction  at 
Salisbury,  in  England. 

If  we  pass  to  the  continent  of  Asia,  we  shall  find  irrigation 
practiced  over  a  wide  extent  of  territory  in  many  countries,  but 
nowhere  on  so  large  a  scale  as  in  the  ancient  and  modern  develop- 
ments in  India.  How  wide  the  extent  of  irrigation  is  in  India 
may  be  most  easily  comprehended  from  the  map,  Fig.  18,  where, 
from  Lahore,  in  the  northwest,  to  Calcutta,  in  the  southeast,  a 
distance  of  nearly  1,400  miles,  and  covering  a  mean  width  not  less 
than  100  miles,  a  large  share  of  the  land  is  under  irrigation. 
Other  modern  irrigation  works  are  to  be  found  at  Cuttack,  on  the 


78 


Irrigation   and    Drainage 


Mahanadi  River,  and  farther  south,  at  various  points  in  the  Madras 
Presidency.  On  the  western  side  of  the  peninsula,  too,  back  from 
Bombay,  both  at  Poona,  in  the  valley  of  the  Mutha  River,  and  at 


Fig.  17.     Ridged  surface  of  a  water-meadow,  Salisbury,  England. 

Bhutan,  where  there  is  a  great  dam  4,067  feet  long  and  130  feet 
high,  which  forms  a  reservoir  for  the  supply  of  the  Nira  canals, 
are  other  extensive  modern  irrigation  systems.  The  Vir  weir,  at 
the  head  of  the  Nira  canal,  is  2,340  feet  long,  with  a  maximum 
height  above  the  river  bed  of  40  feet,  and  over  this  weir,  at  maxi- 
mum flood,  there  pours  160,000  cubic  feet  of  water  per  second,  in 
a  sheet  8  feet  deep  over  the  crest. 

The  number  of  wells  used  for  irrigation  in  the  Madras  Presi- 
dency has  been  estimated  at  not  less  than  400,000,  while  the  area 
they  serve  is  placed  at  2,000,000  acres.  It  is  further  estimated  for 
the  whole  Indian  peninsula,  British  and  native,  that  not  less  tlmn 
300,000  shallow  wells  are  in  use,  while  they  serve  certainly  more 
than  6,000,000  acres  of  land. 

Referring,  now,  more  particularly  to  the  extent  of  irrigation 
enterprises  in  India,  we  learn  from  Richard  J.  Hinton's  report  to 
the  Senate  that  in  the  Madras  Presidency,  with  a  population  of 


80  Irrigation   and    Drainage 

over  31,000,000,  the  irrigation  works,  up  to  1890,  involved  an 
invested  sum  amounting  to  $32,488,000,  and  the  acreage  watered 
in  1889-90  is  placed  at  6,000,000.  In  lower  Bengal,  the  same 
year,  560,000  acres  were  under  cultivation  by  irrigation  ;  while  in 
the  Soane  Circle  system,  2,611,000  acres  were  served,  1,305,000  of 
which  produced  rice. 

The  Ganges  system  is  among  the  greatest  in  India.  The 
Upper  Ganges  has  890  miles  of  main  canals,  with  3,700  distribu- 
taries and  17  great  dams,  and  serves  1,205,000  acres,  the  system 
costing  $14,644,000.  The  lower  Ganges  embraces  531  miles  of 
main  canal  and  1,854  distributaries,  serving  620,000  acres,  and 
costing  $7,000,000. 

In  the  Bombay  Presidency,  in  1889-90,  839,000  acres  were 
irrigated,  and  915,000  acres  were  under  the  public  canals,  whose 
total  cost  is  placed  at  $10,792,000. 

In  the  Punjab  and  Sind,  many  ancient  works  dating  from  the 
twelfth  and  thirteenth  centuries  are  still  in  partial  operation,  but 
the  great  famine  years  of  1831-32  have  brought  about  many 
changes  and  great  improvements.  The  West  Jumna  canal  had 
cost,  up  to  1890,  $8,000,000,  and  it  embraces  84  miles  of  main 
canal  and  1,110  miles  of  distributaries,  or  1,194  in  all.  This, 
Vith  the  East  Jumna  canal,  controlled  2,000,000  acres,  and 
brought  the  Indian  Government  in  1889  90  a  revenue  or  land 
tax  of  $96,000,000.  To  this  same  system  belongs  the  Doab  canal, 
running  parallel  with  the  Jumna  river  through  450  miles,  and 
with  its  1,112  miles  of  distributaries  and  130  miles  of  main 
canals,  serving  580,000  acres  of  land  which  can  be  cultivated.  It 
is  said  that  the  total  expenditure  in  these  provinces  for  irrigation 
purposes  is  represented  by  $36,400,000,  covering  about  6,000,000 
acres,  one-half  of  which  is  under  irrigation  each  year.  It  is 
further  represented  that  for  60  years  these  investments  of  capital 
have  realized  an  annual  return  of  8  per  cent. 

It  is  stated  that  the  total  expenditure  under  British  direction 
in  the  Punjab,  Swat,  Sirhind,  Sind,  and  the  sub-Himalayan 
region,  has  been  not  less  than  $64,000,000,  with  about  2,500  miles 
of  canals  in  operation  in  1890.  But,  besides  these,  there  are  in 
the  same  districts  many  private  canals  and  a  very  large  num- 


Irrigation  in  Asia  81 

ber  of  wells,  which  supply  from  4,000  to  6,000  gallons  each  24 
hours. 

In  the  Indus  valley,  there  are  many  small  canals,  ranging 
from  8  to  16  miles  in  length,  having  a  sum  total  of  709  miles, 
which  supply  water  to  214,000  acres.  Three  other  important 
systems  supply  411,000  acres,  with  a  total  length  of  channel 
amounting  to  1,479  miles.  The  Lahore  branch  of  the  Bari-Doab 
canal  irrigates  523,000  acres,  besides  supplying  the  water  needed 
by  1,352  villages.  The  cost  of  these  works  in  1889-90  had  reached 
$7,872,000,  while  the  year's  net  proceeds  of  the  water  supply  was 
$873,000,  with  an  associated  expenditure  of  $288,000. 

In  the  province  of  Orissa,  with  an  area  of  24,000  square  miles 
and  a  population  of  4,250,000,  there  were,  in  1889-90,  511,000 
acres  of  land  under  the  canal  systems,  ready  for  irrigation. 

Aside  from  these  Anglo-Indian  enterprises  to  which  reference 
has  been  made,  Hinton  states  that  the  native  or  independent 
states  of  India  comprise  two-thirds  of  the  peninsula,  and  that 
their  peoples  are  extensive  irrigators.  The  most  advanced  of 
these  states,  viewed  from  the  standpoint  of  agriculture  and  irri- 
gation, is  Jaipur,  with  an  area  of  14,463  square  miles  and  a 
population  of  2,500,000.  It  has  108  separate  systems  of  irrigation 
works,  with  364  miles  of  mam  canals  and  422  miles  of  distribu- 
taries. In  the  native  state  of  Mysore,  there  are  1,000  miles  of 
irrigation  canals  and  20,000  village  tanks. 

In  the  island  of  Ceylon,  a  decided  effort  has  been  and  is  being 
made  to  restore  and  to  extend  the  ancient  irrigation  systems, 
which  have  been  allowed  to  fall  into  ruin.  The  British  authori- 
ties in  1891  had  already  restored  2,250  of  the  small  and  59  of  the 
large  tanks  or  reservoirs  ;  they  have  constructed  245  wiers  and 
700  miles  of  canals.  There  are  now  over  5,000  ancient  reser- 
voirs in  the  island,  and  one  king,  in  the  twelfth  century,  is 
credited  with  having  had  constructed  4,770  tanks  and  543  great 
canals. 

In  Australia,  work  seems  to  be  largely  prospective  as  yet,  with 
but  few  results  actually  attained.  But  there  are  some  500,000 
acres  in  Victoria  to  be  served  by  irrigation  works  which  are  in 
progress.  In  New  South  Wales,  the  amount  of  land  in  1891 


82  Irrigation  and   Drainage 

actually  irrigated  is  said  not  to  exceed  3,000  acres,  but  provision 
is  being  made  under  government  aid  for  the  irrigation  of  38,000 
acres.  In  South  Australia,  there  are  about  5,000  acres  now  under 
irrigation,  and  a  company  has  been  organized  for  the  develop- 
ment of  an  irrigation  system  on  the  Murray  River,  to  place  under 
ditch  200,000  acres.  Up  to  June,  1891,  the  government  had  sunk 
15  artesian  wells,  8  of  which  are  flowing  and  yielding  from  8,228 
to  3,000,000  gallons  in  24  hours.  These  are  in  Queensland,  and 
in  the  same  region  there  are  86  private  artesian  flowing  wells. 

In  China,  irrigation  has  a  very  extended  and  general  distri- 
bution. The  great  canal  systems  are  laid  out  primarily  for 
transportation,  but  are  used  jointly  and  generally  for  irrigation 
as  well.  It  is  said  the  most  scrupulous  care  is  taken  to  save  and 
utilize  every  source  of  water  in  cultivation  ;  and  in  southern  and 
central  China  it  is  estimated  than  an  acre  of  land  is  made  to  sup- 
port from  three  to  five  persons. 

In  the  provinces  of  Ningpo,  Fo-Kien  and  Shanghai,  the  water 
is  generally  taken  from  small  ditches  led  out  from  the  streams  or 
larger  canals,  or  they  are  fed  from  springs  in  the  hilly  country. 
It  is  said  that  in  very  many  parts  almost  every  farm  is  supplied 
from  canals  or  shallow  laterals,  which  are  2  or  3  miles  long 
and  from  10  to  30  feet  wide,  leading  out  at  right  angles  from  the 
main  canals,  often  from  200  to  400  feet  apart.  It  se'ems,  from  the 
written  accounts,  that  a  large  part  of  the  water  used  by  the  gar- 
deners, and  even  on  the  small  but  numerous  rice  fields,  is  raised 
out  of  the  canals  and  streams  or  ponds  by  a  species  of  chain 
or  rope  pump,  worked  either  by  hand  or  by  oxen,  and  in  the 
irrigation  season,  when  water  is  needed,  they  are  run  at  night 
as  well  as  day.  It  is  even  said  that  water  for  irrigating  is  carried 
considerable  distances  at  times  and  places,  in  buckets  on  a  yoke 
placed  on  the  shoulders  of  men. 

In  the  province  of  Fo-Kien,  where  the  rainfall  is  both  quite 
large  and  well  distributed,  irrigation  is  still  practiced,  but  as  a 
means  of  insuring  larger  yields  rather  than  a  necessity. 

In  Japan,  as  well  as  in  China,  irrigation  is,  and  has  been  from 
time  immemorial,  extensively  practiced,  and  it  is  estimated  that  not 
less  than  two-thirds  of  the  12,500,000  acres  of  land  tinder  culti- 


Irrigation   in  Asia  83 

vation,  supporting  41,000,000  people,  is  under  irrigation  ;  that  is 
to  say,  water  is  artificially  applied  to  not  less  than  8,000,000  acres 
of  land  in  Japan. 

On  the  island  of  Lew  Chew,  belonging  to  Japan,  the  greatest 
care  is  exercised  to  utilize  the  water  of  all  the  short  streams, 
wherever  they  are  found.  On  the  slopes  and  in  the  narrow  val- 
leys, the  lands  are  carefully  leveled  by  terracing,  to  avoid  washing 
and  to  cause  the  water  to  spread  evenly  over  the  surface  of  the 
ground,  and  thus  become  most  effective.  On  the  margins  of  the 
terraces  are  slight  ridges,  which  are  given  permanency  of  form 
by  being  covered  with  grass  ;  these  are  boundaries  and  foot-ways, 
as  well  as  barriers  against  land  washing.  It  is  said  that  dams 
are  not  used  upon  the  streams,  but  in  times  of  high  water  the 
terracing  has  been  such  that  the  water  can  be  at  once  spread  out 
over  the  cultivated  areas,  and  gently  let  down  to  the  lower  levels 
and  back  into  the  main  channels,  after  having  done  its  work  of 
saturating  and  fertilizing  the  fields.  In  order  that  nothing  shall 
be  lost  by  way  of  washing,  there  is  a  lower  waterway  around  the 
margin  of  the  terraced  areas,  which  conducts  the  water  to  one 
corner,  where  it  passes  to  the  next  terrace  below,  but  first  flowing 
through  a  sort  of  settling  basin  partly  filled  with  vines  or  rubbish, 
whose  purpose  it  is  to  collect  the  silt,  to  be  used  in  compost  heaps 
for  manure.  At  the  lowermost  level,  before  the  water  finally 
enters  the  stream,  there  is  a  larger  settling  basin,  through  which 
the  water  must  pass  and  drop  whatever  of  value  it  may  still 
be  carrying  where  it  may  be  recovered  and  used. 

In  writing  of  irrigation  in  Siam,  Consul -General  Jacob  T. 
Child  states  that  about  one -half  of  that  country  is  under  cultiva- 
tion, and  of  this  four -fifths  are  irrigated,  much  of  it  for  rice. 
The  fields  are  supplied  with  water  from  canals,  which  branch  out 
from  the  rivers  in  all  directions,  and  the  main  lines  are  con- 
structed by  the  general  government,  but  those  supplying  the 
individual  fields  directly  are  made  by  the  individual  land 
owners.  Where  the  land  is  government  property,  there  is  an 
annual  rental  of  about  28  cents  per  ri,  or  84  cents  per  acre, 
including  the  use  of  the  water. 

Irrigation  in  other  parts  of  Asia  at  the  present  time,  as  is 


84  Irrigation  and    Drainage 

the  case  both  in  Japan  and  China,  is  carried  on  in  a  small  way 
largely  by  individual  effort,  but  is  widely  and  irregularly  scattered, 
so  that  it  is  difficult  to  form  any  exact  or  even  adequate  estimate 
of  the  extent  of  such  irrigation  ;  and  the  same  statement  is  also 
true  of  British  India  outside  of  the  organized  enterprises  of 
English  capital.  Indeed,  it  must  be  said  that  all  through  Asia 
Minor  and  Central  Asia  isolated  and  individual  irrigation  plants 
are  to  be  found,  which  in  the  aggregate  would  sum  up  a  grand 
total.  Irrigation  is  carried  on  in  this  individual  way  in  Corea,  in 
Afghanistan,  and  parts  of  Eussian  Central  Asia.  It  is  even  to  be 
found  in  Thibet  and  on  the  Pamir,  "The  Roof  of  the  World," 
12,000  feet  above  sea  level.  Nor  can  it  be  said  that  this  irriga- 
tion is  carried  on  only  in  those  places  where  water  is  most  easily 
obtainable,  for  it  is  sometimes  secured  under  conditions  so  labo- 
rious that  few  Americans  would  think  of  undertaking  the  task.  In 
parts  of  Armenia,  for  example,  where  underground  water  is 
abundant,  and  where  the  ground  is  sloping,  it  is  a  common  prac- 
tice to  dig  a  line  of  wells  extending  down  the  slope  and  then,  by 
connecting  the  bottoms  of  these  wells  by  a  tunnel  leading  out 
upon  the  surface  at  a  lower  level,  the  water  becomes  available  for 
irrigation,  and  is  collected  in  reservoirs,  to  be  used  as  needed. 
Water  is  thus  collected  and  brought  to  the  surface  of  the  ground 
by  gravity,  even  in  sections  where  the  uppermost  wells  must  be 
sunk  to  depths  as  great  as  80  to  100  feet.  The  same  practice  also 
is  said  to  exist  in  the  mountainous  parts  of  Afghanistan,  Cashmere, 
and  other  parts  of  Central  Asia,  and  these  underground  water 
channels  are  often  of  considerable  length,  and  many  miles  in 
the  aggregate  have  been  constructed. 

On  the  continent  of  Africa,  the  most  extended  system  is,  of 
course,  that  found  in  Egypt,  developed  along  the  valley  and 
delta  of  the  Nile.  Willcocks  tells  us,  in  his"Egyptain  Irriga- 
tion," that  the  cultivated  or  irrigated  area  in  this  long,  narrow 
valley  is  4,955,000  acres,  while  the  total  area  which  is  below  the 
level  of  flood  waters,  and,  therefore,  capable  of  irrigation,  is 
6,400,000  acres.  This  irrigated  area  is  confined  at  present  to  a 
long  and  relatively  very  narrow  strip  bordering  the  course  of  the 
stream,  and  the  naked  desert  sands  on  both  sides  come  up  sharp 


Irrigation  in  Africa  85 

against  the  watered  area,  which  begins  at  Assuan,  some  500  miles 
from  the  sea,  not  following  the  windings  of  the  Nile.  The  popu-  ^ 
lation  of  this  country  is  now  given  as  5,000,000,  but  it  has  been 
estimated  that  Egypt  once  supported  20,000,000  inhabitants  ;  and 
a  practice  of  today,  which  will  seem  strange  to  the  reader,  is 
that  of  digging  up  the  rubbish  piles  on  the  sites  of  ancient  vil- 
lages, towns  and  cities,  which  represent  the  waste  of  the  millions 
who  have  passed  away,  and  using  this  as  manure  to  fertilize  the 
fields  now  under  irrigation.  The  dry  climate  of  this  country  has 
preserved  these  materials  from  complete  decay,  and  the  site  of 
old  Cairo  is  now  being  dug  over  to  enrich  the  fields  for  miles 
around. 

The  mean  daily  discharge  of  water  which  passes  from  Upper 
Egypt,  at  Cairo,  into  Lower  Egypt  is  estimated  at  8,830,000,000 
cubic  feet,  but  as  large  as  this  amount  is,  it  would  require  20 
days  to  place  Wisconsin  under  an  inch  of  water. 

In  the  Algerian  Sahara,  since  the  sinking  of  the  first  artesian 
well,  in  1848,  at  Biskra,  by  M.  Henri  Fournel,  the  work  went  for- 
ward, until  in  1875  there  had  been  615  wells  put  down,  having 
an  average  depth  of  145  feet,  404  of  which  are  in  the  province  of 
Constantine,  194  in  the  province  of  Algiers,  and  15  in  that  of 
Oran.  A  strange  thing  about  these  artesian  waters  is  the  pres- 
ence in  them  of  nitrates,  and  irrigation  with  them  has  brought 
upon  the  desert  sands  wonderful  oases,  43  in  number  in  the  Oued 
Rir,  supporting,  in  1885,  520,000  date  palms  of  bearing  age,  140,- 
000  palms  from  one  to  seven  years  old,  and  about  100,000  other 
fruit  trees. 

On  the  south  side  of  the  equator,  in  Africa,  there  has  as  yet 
but  little  been  done  in  the  way  of  irrigation,  although  in  Cape 
Colony  efforts  are  being  made.  In  1889  the  U.  S.  Consul  at  Cape 
Town,  Geo.  F.  Hollis,  states  that  the  most  complete  storage  work 
now  constructed  in  the  colony,  and  the  most  important,  is  that  at 
Van  Wyck's  Vley.  The  rainfall  in  this  section  is  very  irregular, 
the  average  for  11  years  being  10  inches.  The  reservoir  has  de- 
pended upon  a  catchment  area  of,  say,  240  square  miles,  but  this 
has  been  found  inadequate,  and  a  furrow  is  now  nearly  com- 
pleted to  bring  over  water  from  a  neighboring  river,  by  which  it 


86  Irrigation  and   Drainage 

is  estimated  that  the  water-covered  area  will  be  increased  to  19 
square  miles,  with  a  depth  of  27  feet.  The  land  under  irrigation 
is  owned  by  the  government,  and  is  leased  at  a  minimum  rate  of 
10  shillings  per  acre. 

In  the  island  of  Madagascar,  on  the  east,  and  that  of  Madeira, 
on  the  west  of  Africa,  irrigation  is  also  practiced  ;  in  the  former 
for  rice  culture  only,  and  by  the  system  of  flooding  ;  but  in  Ma- 
deira the  system  is  both  elaborate  and  extensive,  covering  over 
one -half  of  the  whole  island,  or  120  square  miles.  There  are  no 
catchment  basins  or  reservoirs  other  than  those  which  nature  has 
provided,  and  the  water  used  is  that  which  the  soil  collects  dur- 
ing the  rainy  season  and  gives  up  in  the  form  of  springs.  The 
water  carriers  have  been  constructed  with  care  and  skill,  and 
some  of  them  have  a  length  of  60  or  70  miles.  The  thrifty 
farmers  have  on  their  lands  reservoirs  into  which  they  collect 
their  share  of  water  when  it  is  delivered  to  them,  and  from  this 
distribute  it  to  their  several  crops  as  they  desire ;  but  the  poorer 
class,  who  cannot  afford  the  reservoir,  are  obliged  to  use  the  water 
directly  as  it  comes  to  them,  and  as  the  intervals  are  long  be- 
tween the  delivery  of  water  they  are  not  able  to  make  the  best  use 
of  that  which  they  get,  and  their  crops  suffer  in  consequence. 

In  the  Pacific  Ocean,  too,  there  are  islands  in  which  irrigation 
is  practiced  with  great  skill  outside  of  those  of  Japan,  to  which 
reference  has  already  been  made.  Among  these  may  be  men- 
tioned those  of  Hawaii,  and  the  development  of  the  sugar  industry 
there  has  in  recent  years  led  to  a  corresponding  development  of 
the  facilities  for  irrigation,  as  would  be  expected  when  it  is  stated 
that  adequate  irrigation  there  has  increased  the  yield  of  sugar 
from  2  tons  to  4  tons  per  acre.  It  is  stated  that  there  are  about 
90,000  acres  under  cane,  one-half  of  which  is  irrigated  ;  some 
7,000  acres  of  rice,  and  5,000  acres  of  bananas,  the  rice  being  all 
under  water.  The  water  supply  comes  from  mountain  streams, 
with  their  reservoirs,  and  from  springs  and  artesian  wells. 

The  artesian  wells  about  Pearl  Harbor  are  among  the  largest, 
yielding  an  enormous  quantity  of  water,  sufficient  to  irrigate 
20,000  acres  of  rice  and  a  large  area  of  bananas  and  other  products 
besides.  There  have  been  100  of  these  wells  sunk  about  the  mar- 


Irrigation  in  America  87 

gin  of  this  island,  21  to  42  feet  above  ocean  level,  in  the  last  12 
years,  and  four  of  them  are  said  to  yield  water  enough  for  a  city 
of  165,000  inhabitants. 

In  the  island  of  Java,  too,  irrigation  is  extensively  practiced, 
and  regarding  the  island  of  Lombock,  still  to  the  east  of  Java, 
Mr.  Arthur  B.  Wallace  writes  :  "It  was  here  that  I  first  obtained 
an  adequate  idea  of  one  of  the  most  wonderful  systems  of  cultiva- 
tion in  the  world,  equaling  all  that  is  related  of  Chinese  industry, 
and,  as  far  as  I  know,  surpassing,  in  the  labor  bestowed  on  it, 
any  tract  of  equal  extent  in  the  most  civilized  countries  of  Europe. 
I  rode  through  this  strange  garden  utterly  amazed,  and  hardly 
able  to  realize  the  fact  that  in  this  remote  and  little  known  island, 
Lombock,  from  which  all  Europeans  (except  a  few  traders  at  the 
port)  are  jealously  excluded,  many  hundreds  of  square  miles  of 
irregularly  undulating  country  have  been  so  skillfully  terraced  and 
leveled  and  permeated  by  artificial  channels  that  every  portion  of 
it  can  be  irrigated  and  dried  at  pleasure." 

Passing,  now,  to  the  American  continent,  we  have  already 
referred  to  its  prehistoric  irrigation  works,  and  to  the  extensive 
and  complete  systems  of  irrigation  found  in  South  America  before 
the  occupancy  of  that  continent  by  the  Spanish  and  Portuguese, 
for  irrigation  was  practiced  there  on  both  slopes  of  the  great 
Andean  ranges.  It  must  be  said,  however,  to  the  shame  of  our 
boasted  civilization,  that  a  very  large  share  of  those  extensive 
and  valuable  improvements  have  been  allowed  to  pass  into  ruin, 
and  now  must  be  restored  at  great  cost. 

In  the  Argentine  Republic,  lying  between  20°  and  56°  south 
latitude,  irrigation  is  being  practiced  in  the  provinces  of  Cordoba, 
San  Luis,  Mendosa,  San  Juan,  Catamarca,  Rioja,  Santiago  del 
Estero,  Tucman,  Salta  and  Jujuy  ;  and  it  is  stated  that  the  total 
area  under  cultivation  by  irrigation  will  exceed  1,759,600  acres. 
According  to  Consul  Baker's  report,  works  were  begun  about 
1882-83  on  a  number  of  large  dams  and  canals,  using  the  water 
of  four  important  rivers,  at  an  estimated  cost  of  $15,280,000, 
which  were  expected  to  have  an  aggregate  capacity  equal  to  about 
3,020,000  acres. 

While   there  are    large   areas    in  the   aggregate   irrigated    in 


88  Irrigation  and   Drainage 

other  parts  of  South  America,  Central  America  and  Mexico,  no 
very  definite  idea  of  its  magnitude  or  distribution  can  be  given 
as  yet. 

Newell  says,  in  the  report  of  the  Eleventh  Census,  that  in 
the  western  part  of  the  United  States  the  area  irrigated  within  the 
arid  and  sub -humid  regions  aggregated  at  the  end  of  May, 
1890,  3,631,381  acres,  or  5,674.03  square  miles,  while  the  total 
number  of  farms  or  holdings  upon  which  crops  were  raised  by 
irrigation  was  54,136.  In  this  irrigation,  water  was  supplied  by 
3,930  wells  to  51,896  acres,  at  an  average  cost  of  $245.58  per  well, 
the  wells  yielding  an  average  of  54.43  gallons  per  minute.  The 
average  value  of  products  from  this  irrigated  land  per  acre  he 
found  to  be  $14.89,  the  farms  having  an  estimated  mean  value 
per  acre  of  $83.28,  while  the  average  size  of  each  farm  or  holding 
was  67  acres.  The  average  value  of  the  product  of  the  average 
farm  was  thus  $897.63. 

To  bring  together  in  close  review  the  extent  of  irrigation  as 
it  is  today  practiced  in  the  various  parts  of  the  world,  we  may 
quote  the  statements  of  Wilson  :  w  The  total  area  irrigated  in 
India  is  about  25,000,000  acres,  in  Egypt  about  6,000,000  acres, 
and  in  Italy  about  3,700,000  acres.  In  Spain  there  are  500,000 
acres,  in  France  400,000  acres,  and  in  the  United  States  4,000,000 
acres  of  irrigated  land.  This  means  that  crops  are  grown  on 
40,000,000  acres  which,  but  for  irrigation,  would  be  relatively  bar- 
ren or  not  profitably  productive.  In  addition  to  these,  there  are 
some  millions  more  of  acres  cultivated  by  aid  of  irrigation  in 
China,  Japan,  Australia,  Algeria,  South  America,  and  elsewhere." 

These  figures  seem  enormous  as  we  read  them,  and  so  they 
are,  but  they  leave  an  exaggerated  impression  on  the  mind  which 
needs  to  be  corrected,  for  very  few  realize  the  magnitude  of  the 
volume  of  water  which  must  be  handled  in  raising  a  crop  by  irri- 
gation. In  order  that  we  may  not  mislead  in  this  direction,  we 
wish  to  make  the  correction.  Let  us  suppose  that  the  amount  of 
land  which  is  actually  under  irrigation  at  the  present  time  is  four 
times  the  40,000,000  of  acres  which  have  been  enumerated  above. 
Now,  were  this  supposition  true,  and  all  of  these  acres  were 
brought  together  in  one  solid  square,  it  would  have  but  500  miles 


Climatic   Conditions  89 

jn  a  side.  But  to  cover  such  an  area  as  this  with  2  inches  of 
water  once  in  10  days  would  require  more  than  three  Nile  rivers 
flowing  at  maximum  flood — a  river  50  feet  deep,  1.156  miles  wide, 
running  three  miles  an  hour. 

THE   CLIMATIC    CONDITIONS   UNDER   WHICH   IRRIGATION 
IS   PRACTICED 

If  we  study  the  conditions  of  rainfall  under  which 
irrigation  has  been  practiced,  we  shall  find  rather  wide 
variations  in  the  mean  amounts  which  fall  upon  the  dif- 
ferent countries,  especially  when  the  mean  annual  rain- 
falls are  compared.  In  all  of  India  except  the  extreme 
northwest  part;  throughout  China,  Japan  and  Siam, 
in  Italy,  and  France,  and  Mexico,  as  much  rain  falls 
during  the  year  as  falls  in  the  United  States  east  of 
the  97th  meridian,  if  we  except  Louisiana,  Mississippi, 
Georgia  and  Florida, —  an  amount  ranging  from  23.6 
inches  to  51.2  inches,  or  between  60  and  130  centime- 
ters. But  in  Asiatic  Turkey,  Persia,  Afghanistan  and 
the  extreme  northwest  of  India ;  in  the  irrigated  parts 
of  Queensland,  Victoria  and  South  Australia ;  in  Cape 
Colony,  Algiers  and  Spain;  and  in  Argentina  and  the 
western  United  States,  south  of  Washington  state,  the 
rainfall  for  the  year  drops  from  23  inches  to  less  than 
8  inches.  On  the  lower  Gauges,  from  the  Soane  region 
to  Calcutta,  and  south  along  the  east  coast  as  far  as  the 
Orissa  canals,  the  yearly  rainfall  is  equal  to  that  of  the 
southern  states,  or  from  51  inches  to  78  inches  (130  to 
200  centimeters) .  It  is  not,  therefore,  in  regions  of 
small  rainfall  alone  that  irrigation  systems  have  been 
developed.  Indeed,  there  must  always  be  contiguous 


90  Irrigation  and    Drainage 

territory  of  considerable  rainfall,  in  order  to  fill  the  soil 
and  give  rise  to  springs,  streams,  and  wells,  or  there 
could  be  no  water  for  irrigation.  It  is  only  the  accident 
of  a  great  stream  like  the  Nile,  gathering  its  waters  in  a 
region  of  large  rainfall,  that  makes  any  irrigation  at  all 
possible  in  a  rainless,  desert  country  like  Upper  and 
Lower  Egypt. 

The  distribution  of  the  rainfall  with  reference  to  the 
growing  season,  more  than  the  quantity  of  it,  is  the 
chief  factor  in  determining  whether  irrigation  will  be 
profitable  or  not.  In  the  irrigated  districts  of  Italy, 
Spain,  France,  Austria -Hungary,  Algiers,  Cape  Colony, 
Asia  Minor,  Armenia,  Victoria,  South  Australia,  and 
the  westernmost  part  of  the  United  States,  there  is  a 
tendency  to  a  dry  time  in  early  or  late  summer,  at  the 
time  when  crops  need  water  most,  or  in  some  of  these 
countries  it  may  be  dry  the  whole  season  through,  the 
rainy  season  being  in  fall  or  winter.  In  China,  south- 
ern Japan,  Siam  and  Ceylon  the  summer  is  rainy,  but 
there  is  a  tendency  to  develop  a  short  dry  season  in 
midsummer.  In  Switzerland,  Belgium,  Denmark,  Eng- 
land, Bavaria,  Madagascar,  North  Japan,  Queensland, 
and  Mexico  there  is  usually  a  uniform  distribution  of 
rain  throughout  the  whole  of  the  growing  season.  In 
these  latter  countries,  however,  while  irrigation  is  prac- 
ticed in  them,  it  must  be  said  that  it  is  supplementary 
rather  than  a  necessity. 


CHAPTER   II 

THE  CONDITIONS    WHICH   MAKE   IRRIGATION  IMPERA- 
TIVE,  DESIRABLE    OR    UNNECESSARY 

To  understand  the  conditions  which  make  it  im- 
perative, desirable  or  unnecessary  to  irrigate  land,  it 
is  important  to  have  clearly  in  mind  the  various  objects 
which  may  be  attained  by  the  application  of  water  to 
cultivated  fields. 

THE     OBJECTS     OF     IRRIGATION 

The  first  and  primary  object  to  be  attained  in  irri- 
gating the  soils  of  arid  climates  is  to  establish  those 
moisture  relations  which  are  essential  to  plant  growth, 
and  the  same  fundamental  object  will  usually  stand 
first  in  sub -humid  climates,  as  it  may  even  in  those 
which  are  distinctly  humid ;  for  in  the  sub -humid 
climates  it  very  often  happens  that  the  intervals 
between  rains  of  sufficient  quantity  are  so  long  that 
almost  any  crop  may  suffer ;  and  in  humid  climates 
there  are  certain  crops,  like  the  cranberry  and  rice, 
which  profit  by  more  or  less  protracted  inundations  ; 
or,  again,  like  the  pineapple,  growing  upon  extremely 
leachy  sands,  which  can  retain  but  a  small  quantity 
of  water  even  for  a  single  day,  and  where  it  is  neces- 

(91) 


92  Irrigation   and    Drainage 

sary  that  even  frequent  showers  shall  be  supplemented 
in  order  that  the  best  results  may  be  attained. 

In  the  second  place,  lands  may  be  irrigated  in  any 
climate,  when  it  is  desired  to  carry  to  the  land  ferti- 
lizing matter  which  the  irrigation  waters  may  hold  in 
solution  or  in  suspension.  The  extreme  cases  of  this 
practice  are  where  cultivators  take  advantage  of  the 
large  amounts  of  plant -food  which  are  borne  along 
in  the  waters  of  streams  into  which  the  sewage  of 
great  cities,  like  Paris  or  Edinburgh,  are  discharged. 
Such  waters  are  extremely  fertile,  even  when  much 
diluted.  In  emphasis  of  this  fact,  Fig.  19  shows  a 
field  of  heavy  grass  growing  on  the  Craigentinny 
meadows  of  Edinburgh.  This  ground  yields  from  three 
to  five  such  crops  each  year,  and  has  done  so  for 
nearly  a  century,  with  no  other  fertilization  than  that 
which  comes  to  it  through  the  winter  and  summer 
application  of  diluted  sewage  water.  Hence  we  need 
not  be  surprised  that  such  lands  have  rented  as  high 
as  18  to  22  pounds  sterling  for  the  season  per  acre, 
when  the  rentals  are  sold  at  auction  to  the  highest 
bidder. 

But  ordinary  river  waters  are  widely  used  in  vari- 
ous countries,  chiefly  for  the  fertilization  of  water 
meadows.  The  amount  of  water  applied  in  a  year 
is  in  some  sections  very  great,  reaching,  in  the  Vosges, 
in  France,  over  300  feet  in  depth  per  year.  It  is 
during  the  colder  portions  of  the  year,  when  the  grass 
is  not  growing,  that  the  larger  part  of  the  water  is 
applied,  depending  upon  the  absorptive  and  retentive 
power  of  the  soil  to  abstract  from  the  water,  as  it 


Objects    of  irrigation 


93 


passes  over  and  leaches  through,  enough  of  potash, 
phosphoric  acid,  and  other  ingredients  of  plant -food, 
to  hold  the  strength  of  the  soil  up  to  a  uniformly  high 
standard,  even  when  constant  cropping  is  practiced. 


Fig.  19.    Heavy  growth  of  grass  on  the  Craigeutiuny  meadows, 
Edinburgh,  Scotland. 

A  third  object  in  irrigation,  in  certain  classes  of 
cases,  is  primarily  to  change  the  texture  of  the  soil. 
When  soils  are  very  sandy  and  open,  having  so  small 
a  water  capacity  that  not  enough  is  retained  for  the 
growth  of  most  crops,  then  the  leading  of  the  water  of 
a  turbid  stream  over  such  lands  results  in  the  deposition 
of  silt  to  such  an  extent  as,  in  the  course  of  time,  to 


94  Irrigation   and    Drainage 

very  materially  improve  their  physical  condition  ;  but 
at  the  same  time  giving  to  these  soils  a  large  amount 
of  plant -food,  for  the  material  borne  along  in  suspen- 
sion in  the  water  of  rivers  is  usually  very  valuable, 
derived,  as  it  is,  from  the  finest  and  best  parts  of  fer- 
tile soils.  These  ingredients  of  the  flood  waters  of 
the  river  Nile  are  extremely  valuable  to  those  desert 
sands  which,  under  the  long  action  of  strong  winds, 
have  lost  the  major  part  of  those  fine  and  extremely 
important  grains  which  the  sand  storms  of  the  deserts 
have  picked  up  and  swept  away. 

In  the  fourth  type  of  irrigation,  which  is  an  extreme 
case  of  the  last,  the  aim  is  to  flood  low  tracts  of  land 
with  silt -bearing  water  in  large  volume,  and  to  hold  it 
there  until  the  suspended  matters  have  been  deposited, 
so  as  ultimately  to  build  up  the  whole  tract,  raising  it  to 
a  level  at  which  it  may  be  naturally  drained,  or  at  which 
a  depth  of  fertile  soil  sufficient  to  meet  the  needs  of 
agriculture  may  be  laid  down  over  one  which  had  been 
undesirable.  Low-lying  lands  have  been  built  up  by 
this  method  until  in  the  course  of  ten  or  a  dozen  years 
the  whole  surface  has  been  raised  as  much  as  5  to  7  feet. 

A  fifth  type  of  irrigation,  which  has  received  a 
notable  expansion  in  recent  years,  has  for  its  primary 
object  the  rapid  destruction  of  the  organic  matters  held 
in  solution  and  in  suspension  in  the  sewage  waters  of 
cities,  in  order  that  they  shall  reach  river  channels  and 
the  ground -water  of  the  surrounding  country  suffi- 
ciently purified  not  to  endanger  the  public  health  by 
a  pollution  of  drinking  waters,  or  by  developing  un- 
healthful  atmospheric  conditions. 


Water   Needed  for   a    Paying    Crop  95 

THE    LEAST    AMOUNT    OF    WATER    WHICH    CAN    PRODUCE 
A    PAYING    CROP 

In  the  manufacture  of  butter  from  milk,  it  is  a  mat- 
ter of  prime  commercial  importance  to  know  just  how 
much  butter -fat  that  milk  contains,  and  what  is  the 
maximum  amount  of  butter  that  fat  is  capable  of  pro- 
ducing ;  for  only  this  knowledge  can  show  how  closely 
the  manufacturer  is  working  to  his  possible  limit  of 
profit,  and  how  great  his  losses  may  be.  For  a  like  rea- 
son, it  is  very  important  to  know  what  is  the  minimum 
amount  of  water  which,  under  stated  climatic  conditions, 
can  meet  the  needs  of  a  given  crop,  producing  a  paying 
yield.  It  is  important,  because  only  such  knowledge  as 
this  can  show  how  economical  or  how  wasteful  our 
methods  of  tillage  may  be,  and  how  nearly  we  are  realiz- 
ing the  largest  profits  which  are  possible  to  the  business. 

In  the  Introduction,  much  pains  has  been  taken 
to  give  in  detail  the  evidence,  and  the  methods  of  pro- 
curing it,  which  shows  how  much  water  must  be  used 
by  a  given  crop  in  coming  to  maturity  when  placed 
under  the  best  of  conditions.  This  has  been  done, 
because  it  is  a  part  of  the  knowledge  which  is  needed 
to  show  under  what  climatic  conditions  irrigation  may, 
and  under  what  it  may  not,  be  practiced ;  because  it 
is  needed  to  show  how  far  into  the  sub -humid  districts 
agricultural  operations  may  be  pushed  without  the  aid 
of  irrigation ;  because  it  will  help  to  teach  how  far  we 
may  hope,  by  the  practice  of  the  best  methods  of  till- 
age, to  dispense  with  irrigation,  and  avert  disastrous 
results  during  seasons  of  drought. 


96  Irrigation    and    Drainage 

We  have  already  referred  at  some  length  to  the 
seemingly  small  amounts  of  water  used  by  the  wheat 
crop  in  coming  to  maturity  in  the  San  Joaquin  valley, 
in  California,  and  to  the  long  period  of  some  60  days 
at  the  close  of  its  growing  season  during  which  it 
receives  no  water,  either  as  rain  or  by  irrigation. 
What  is  the  minimum  amount  of  water  which  is  capa- 
ble of  producing  a  yield  of  15,  20,  30  or  40  bushels  of 
wheat  per  acre,  and  how  does  this  compare  with  the 
actual  rainfall  of  the  San  Joaquin  valley  ? 

We  have  made  no  observations  with  wheat,  like  those 
which  have  been  recorded  for  oats,  barley,  maize,  clover 
and  potatoes,  but  from  similar  observations  made  by 
Hellriegel,  in  Germany,  it  is  probable  that  the  amount 
of  water  necessary  to  produce  a  ton  of  dry  matter  with 
wheat  is  not  very  far  from  906,000  pounds  or  453  tons, 
equal  to  3.998  acre -inches.  How  many  bushels  of 
wheat  should  this  give  ? 

The  ratio  of  the  dry  weight  of  the  kernels  to  that 
of  the  straw  and  chaff  in  a  crop  of  wheat  has  been 
found  to  be  as  1  to  1.1  in  a  dry  season,  but  to  be  as 
high  as  1  to  1.5  when  there  has  not  been  an  undesir- 
able stimulation  to  the  growth  of  straw.  But  where 
wheat  is  irrigated  in  the  southeast  of  France,  Gasparin 
states  that  a  ratio  of  1  of  grain  to  2  of  straw  is  usual. 

If  we  take  the  ratio  of  1  to  1.5,  and  allow  60  pounds 
to  the  bushel  of  wheat,  we  may  compute  the  least 
amount  of  water  which  is  likely  to  enable  a  crop  of 
varying  yields  per  acre  to  be  produced,  and  the  re- 
sults of  such  a  computation  are  given  in  the  following 
table: 


Water  Needed  for   a    Given    Crop  97 


Table  showing  the  least  amount  of  water  required   to  produce  different  yields  of 
^vheat  per  acre  when  the  ratio  of  grain  to  straw  is  1-1.5 


Wgt.  of  grain 

per  acre  
Wgt.  of  straw 

Total  wgt. 

Water  used 

No.  bushels 

TONS 

TONS 

TONS 

ACRE-IN. 

15 

.45 

.675 

1.125 

4.498 

20 

.6 

.9 

1.5 

5.998 

25 

.75 

1.125 

1.875 

7.497 

30 

.9 

1.35 

2.25 

8.997 

35 

1.05 

1.575 

2.625 

10.495 

40 

1.2 

1.8 

3 

12 

These  amounts  of  water,  given  in  the  last  column 
of  the  table,  are  so  small  that  they  appear  false,  for  the 
quantity  given  for  15  bushels  to  the  acre  is  almost 
covered  by  the  rainfall  of  the  most  arid  parts  of  the 
world.  Several  statements  need  to  be  made  in  order 
to  put  them  in  their  true  light. 

In  the  first  place,  the  figures  could  only  be  true 
when  the  amount  and  kind  of  plant -food  in  the  soil 
is  all  that  the  crop  can  use  to  advantage,  for  no  amount 
of  pure  water  can  make  up  for  such  deficiencies  except 
in  so  far  as  it  makes  more  rapid  the  solution  of  other- 
wise unavailable  plant -food  in  the  soil.  Then,  again, 
the  data  for  the  table  were  procured  under  conditions 
which  permitted  no  loss  of  moisture  from  the  soil, 
either  by  surface  drainage  or  by  downward  movements 
beyond  the  depth  of  root  action.  Further  than  this, 
no  account  is  taken  of  the  water  which  may  have  been 
given  to  the  soil  in  bringing  it  to  the  proper  moisture 
conditions  previous  to  planting  the  crop  in  it.  Water 
enough  was  given  to  the  soil  to  put  it  in  the  right 
condition  to  start  with,  and  the  amounts  in  the  table 


98  Irrigation    and    Drainage 

cover  simply  what  has  been  found  necessary  to  main- 
tain that  amount  against  surface  evaporation  from  the 
soil  under  the  best  of  conditions  and  through  the  crop 
itself.  In  the  San  Joaquin  valley  there  is  a  long  inter- 
val, from  the  end  of  July  until  the  fall  rains  begin 
in  November,  when  some  evaporation  is  taking  place 
from  the  surface  soil,  and  enough  rain  must  have 
fallen  to  bring  the  soil  up  to  a  good  standard  condi- 
tion of  soil  moisture  before  the  crop  is  started  in  it, 
and  the  amounts  in  the  table  would  need  to  be  in- 
creased by  so  much,  at  least,  as  would  be  required 
to  establish  this  condition. 

How  much  water  would  need  to  be  added  to  the 
soil  in  the  San  Joaquin  valley  by  the  fall  rains,  in 
order  to  restore  the  proper  amount  of  soil  water,  or 
how  great  the  evaporation  may  be  between  harvest  and 
seeding  time,  we  do  not  know.  We  do  know,  however, 
that  the  rate  of  evaporation  from  the  surface  of  a  dry 
soil  is  not  very  rapid.  In  illustration  of  this,  it  may 
be  stated  that  after  removing  a  crop  of  oats  from  four 
of  our  cylinders  in  the  field,  a  record  was  kept  of  the 
loss  of  moisture  from  them  between  Aug.  2  and  Aug. 
25,  and  it  was  found  that  the  total  evaporation  from 
7.068  square  feet  was  5.3  pounds.  In  another  case, 
six  cylinders  in  the  field  lost  by  surface  evaporation 
between  Jan.  10,  1894,  and  March  12,  41.8  pounds. 
The  loss  per  100  days  expressed  in  inches  in  the  first 
case  was  .6268,  and  in  the  second  1.243. 

Taking  the  first  of  these  two  figures,  which  is  likely 
to  be  more  nearly  true  for  the  district  in  question,  the 
total  loss  would  be  .79  inches,  and  at  the  second  rate 


Water   Needed  for   a    Given    Crop  99 

it  would  be  1.54  inches.  It  is  certain  that  there  is  a 
further  loss  from  these  soils  which  is  likely  to  be 
nearly  if  not  quite  as  large  as  that  computed,  and  that 
is  the  evaporation  which  takes  place  through  the  grain 
after  coming  to  maturity,  while  it  is  standing  upon  the 
ground  before  being  cut ;  for  it  is  known  that  the 
movement  of  water  through  the  plant  does  not  stop  at 
once  when  the  kernels  have  fully  matured.  Further 
than  this,  if  a  considerable  time  intervenes  between 
the  time  of  the  first  rains  and  the  germination  of  the 
seed,  and  especially  if,  after  the  grain  comes  up,  it 
for  any  reason  makes  an  abnormally  slow  growth,  there 
will  then  be  considerable  additional  losses  which  are 
not  included  in  the  figures  given  in  the  table  ;  and  it 
would  seem  that  the  average  necessary  loss  of  soil 
moisture  from  these  lands  which  in  no  way  contributes 
to  the  growth  of  the  crop  of  wheat  may  easily  be  as 
high  as  3  inches.  If  this  be  true,  the  figures  in  the 
last  column  of  the  table  would  be  nearer  7.5,  9,  10.5, 
12,  13.5  and  15  inches,  respectively,  for  the  differ- 
ent yields,  than  those  stated.  It  is  further  probable 
that  for  the  lighter  yields,  where  the  grain  would  have 
to  stand  thinner  on  the  ground  or  else  the  plants  be 
smaller,  there  would  be  absolutely  more  loss  of  water 
from  the  surface  of  the  soil  itself,  and,  hence,  that  the 
lower  figures  just  given  are  likely  to  be  found  larger 
than  they  are  there  stated. 

The  mean  annual  rainfall  of  the  San  Joaquin- 
Sacramento  valley,  as  given  by  Harrington  in  his  rain- 
fall map,  ranges  from  5  inches  in  the  far  south  to  12 
inches  in  the  north,  this  amount  all  falling  between 


100  Irrigation   and    Drainage 

November  1  and  May  1.  The  tenth  census  gives  the 
average  yield  of  wheat  per  acre  as  6  to  13  bushels  in 
the  south,  and  from  13  to  20  bushels  in  the  northern 
part  of  the  valley.  The  average  yield  in  California 
in  1879,  on  1,832,429  acres,  is  placed  at  16.1  bushels 
per  acre ;  while  it  is  stated  that  certified  records  of 
yields  as  high  as  73  bushels  per  acre  are  recorded  from 
areas  as  large  as  10  acres. 

If  we  consider  the  "dry  farming"  sections  of  the 
state  of  Washington,  where  most  of  the  wheat  grown 
has  been  the  spring  varieties,  sown  in  April,  and  some- 
times as  late  as  May,  and  harvested  in  August  or  early 
September,  we  shall  have  the  growing  season  more 
nearly  the  same  as  that  in  the  corresponding  latitudes  of 
the  humid  parts  of  the  United  States.  Here,  too, 
the  rainfall  in  amount  is  very  nearly  the  same  as  that  of 
the  district  to  the  south  for  the  corresponding  period  of 
time,  but  the  rains  begin  a  month  earlier  and  continue  a 
month  later,  so  that  the  amount  for  the  year  is  from  8.4 
to  13.5  inches,  or  about  33  per  cent  more,  while  the 
mean  yield  per  acre  was  23.4  bushels  in  1879,  as 
against  16.1  bushels  in  California.  There  is  here 
in  Washington,  as  in  California,  a  dry  period  of 
some  60  days,  in  which  the  crop  is  forced  to  come  to 
maturity. 

It  appears,  therefore,  from  the  observations  and 
experiments  regarding  the  number  of  inches  of  water 
which  may  be  used  in  producing  a  ton  of  dry  matter, 
and  from  practical  experience  in  arid  climates,  that  on 
deep,  fertile  soils,  well  managed,  good,  paying  yields  of 
wheat  may  be  realized  where  the  amount  of  rain  is  as 


Like  Rainfalls  not  Equally  Productive          101 

small  as  7  or  8  inches,  and  large  yields  when  it  reaches 
12  to  15  inches,  provided  it  has  a  suitable  distribu- 
tion. 


LIKE     AMOUNTS     OF     RAINFALL    NOT    EQUALLY 
PRODUCTIVE 

In  the  United  States  west  of  the  97th  meridian, 
where  the  rainfall  is  notably  deficient,  except  on  the 
west  side  of  the  Cascade  range  in  Oregon  and  Washing- 
ton, there  are  a  large  number  of  areas  in  which  an  effort 
has  been  made  to  grow  crops  of  one  kind  or  another 
without  irrigation,  and  in  considerable  areas  with 
marked  success,  as  in  the  San  Joaquin- Sacramento  val- 
ley, in  California,  and  in  eastern  Washington  and 
Oregon,  to  which  reference  has  just  been  made.  In  the 
sketch  map,  Fig.  20,  prepared  by  Newell,  the  areas  in 
which  "dry  farming,"  or  farming  without  irrigation, 
has  been  practiced  with  greater  or  less  success,  are 
represented  in  black.  It  will  be  seen  that  this  map 
shows  a  long,  continuous  area,  just  west  of  the  97th 
meridian,  another  one  in  California,  and  a  third  in 
Washington,  besides  very  many  smaller  ones.  These 
three  larger  areas  receive  very  nearly  the  same  amounts 
of  rainfall  for  the  year,  but  the  distribution  of  it  in  time 
is  very  different.  In  California  the  rain  all  falls  in  [the 
six  months,  November  to  April,  inclusive  ;  in  Washing- 
ton it  is  from  October  to  May,  inclusive,  while  in  the 
97th  meridian  region,  much  the  larger  part  of  the  rain 
fails  during  the  months  between  April  and  September. 
The  eastern  region,  therefore,  has  its  moisture  well  dis- 


102 


Irrigation    and    Drainage 


Fig.  20.    The  dry-farming  areas  (in  black)  in  the  western  United  States 
(After  Newell.) 

tributed  through  the  growing  season,  while  both  of  the 
western  areas  mature  their  crops  in  from  30  to  60  days 
of  continuous  nearly  rainless  weather ;  and  yet,  if  we 


Like  Rainfalls  not  Equally  Productive          103 

compare  the  yields  of  barley,  oats,  rye  and  wheat  in 
the  three  districts,  taking  the  Tenth  Census  figures  for 
California,  Washington  and  Kansas  for  comparison, 
the  yields  are  largest  in  Washington  and  smallest  in 
Kansas,  as  shown  below: 

Mean  yield  per  acre  of > 

Barley        Oats  Rye  Wheat 

Washington    38  41  14  23 

California 21  26.8  9  16.1 

Kansas 12.5          19  12  9.3 

Expressing  these  differences  in  percentages,  we  get: 

Washington 100          100          100          100 

California 55.2         65.3         64.3         70 

Kansas 32.9         46.3         85.7         40.4 

As  the  soils  in  the  three  regions  are  notably  fertile, 
and  were  in  1879  very  close,  on  the  average,  to  virgin 
conditions,  the  differences  in  yield  can 'hardly  be  attrib- 
uted to  differences  in  plant -food  other  than  as  influenced 
by  soil  moisture  ;  and  as  the  quantity  of  rain  which  falls 
in  Kansas  during  the  growing  season,  April  to  Septem- 
ber, inclusive,  is  11.5  to  16.8  inches,  while  that  in 
Washington  is  only  8.4  to  13.5  inches,  it  appears  plain 
that  in  some  way  the  available  moisture  is  more  effective 
on  the  Pacific  border  than  it  is  in  the  97th  meridian 
region. 

It  would  be  of  very  great  practical  importance  to 
understand  fully  the  causes  which  permit  so  small  an 
amount  of  rain  as  that  of  eastern  Washington,  falling, 
so  much  of  it,  before  the  growing  season,  to  ensure  the 


104  Irrigation   and    Drainage 

maturity  of  such  large  crops  under  so  clear  a  sky  and  in 
spite  of  so  long  and  continuous  a  period  of  drought, 
while  in  western  Kansas  25  to  38  per  cent  more  rain- 
fall, well  distributed  through  the  growing  season,  pro- 
duces less  than  one -half  the  yield  per  acre.  The  yield 
is  certainly  less  than  one- half,  because  the  averages 
used  for  Kansas  are  too  large  for  the  western  section 
of  the  state,  whose  rainfall  has  been  brought  into 
comparison. 

While  we  are  a  long  way  from  possessing  the  need- 
ful data  for  the  solution  of  this  problem,  some  of  the 
factors  are  evident  enough,  and  may  be  stated  here.  In 
the  first  place,  the  rains  of  the  sections  of  California  and 
of  Washington  under  consideration  fall  in  the  cooler 
portion  of  the  year,  when  the  air  is  more  nearly 
saturated  and  when  the  wind  velocities  are  small, 
while  the  sun  is  much  of  the  time  obscured  by  clouds. 
All  these  conditions  conspire  to  permit  a  large  per 
cent  of  the  water  which  falls  upon  the  ground  to 
enter  it  deeply,  without  being  lost  by  evaporation, 
while  a  deep,  retentive  soil  serves  to  prevent  loss  by 
drainage. 

'In  western  Kansas,  on  the  other  hand,  where  the 
rain  falls  largely  in  the  form  of  showers  in  the  heated, 
sunny  season  of  the  year,  and  where  the  wind  veloci- 
ties are  high  and  the  air  extremely  dry,  it  is  plain  that 
a  much  larger  per  cent  of  water  falling  as  rain  must 
be  at  once  lost  by  evaporation  from  the  surface  of  the 
soil,  before  it  has  had  an  opportunity  to  enter  it  deeply 
enough  to  be  retained  by  soil  mulches. 

In  the  second  place,  a  frequent  surface  wetting  of 


Like  Rainfalls  not  Equally  Productive          105 

the  soil,  such  as  takes  place  in  Kansas,  tends  strongly 
to  hold  the  roots  near  to  the  surface,  where  with  scanty 
mulches  they  are  certain  to  suffer  severely  whenever  a 
period  of  ten  days  without  rain  occurs  ;  and  if,  under 
these  conditions,  the  plant  is  able  to  send  new  roots 
more  deeply  into  the  soil,  they  can  find  there  but  a 
scanty  supply  of  moisture,  because  there  have  been  no 
winter  rains  sufficient  to  produce  percolation.  Then, 
again,  after  such  a  ten -day  drought,  with  the  surface 
roots  now  become  inactive  through  a  dying  off  of  the 
absorbing  root -hairs,  when  the  next  rain  does  fall, 
unless  it  is  a  very  heavy  one,  the  major  part  of  it  will 
be  lost  by  evaporation  from  the  soil,  in  the  case  of 
crops  like  wheat,  oats,  rye  and  barley,  long  before  the 
plants  are  able  to  put  themselves  in  position  to  take 
full  advantage  of  it. 

In  California  and  eastern  Washington,  the  case  is 
radically  different.  There  the  water  gets  well  into  the 
soil  before  the  crop  is  put  upon  the  ground.  Moisture 
enough  is  present  to  produce  germination,  and  the 
roots  develop  at  first  near  the  surface,  when  there  is 
ample  moisture  present ;  but  later,  under  the  rainless 
conditions,  it  is  quite  likely  that  they  advance  more 
and  more  deeply  into  the  ground  as  the  moisture  in 
the  upper  layers  of  the  soil  becomes  too  scanty,  and 
thus  day  by  day  the  effectiveness  of  the  soil -mulch  is 
increased,  while  the  roots  have  only  to  advance  so  far 
as  is  needful  to  allow  capillarity  to  bring  them  the 
water  they  need  from  the  store  which  the  soil  has  re- 
tained. With  these  physical  principles  and  conditions 
set  down  as  foot -lights  to  illuminate  our  problem,  and 


106  Irrigation   and    Drainage 

with  the  other  fact  for  a  side-light  turned  upon  it, 
that  6  inches  of  water,  when  the  crop  can  have  it  to 
use  to  the  best  advantage,  is  enough  to  produce  20 
bushels  of  wheat  to  the  acre,  we  can  see  its  outlines 
with  sufficient  clearness  to  feel  sure  that  more  study 
in  the  field  would  give  us  its  full  solution.  As  the 
matter  now  stands,  the  case  is  sufficiently  clear  that 
we  may  not  conclude,  because  9  to  12  inches  of  rain 
in  California  has  produced  abundant  crops  of  wheat, 
that  a  similar  rainfall  in  the  sub -humid  belt  ought 
to  produce  like  results.  It  should  be  sufficiently 
evident,  also,  that  even  with  the  best  modes  of  till- 
age we  can  hope  to  adopt,  there  will  still  be  much 
more  water  required  per  pound  of  dry  matter  pro- 
duced all  through  the  sub -humid  region,  than  is  de- 
manded under  the  conditions  of  the  lower  San  Joa- 
quin  valley. 

The  same  principles  make  it  very  clear,  also,  that  a 
judicious  application  of  water  by  the  methods  of  irri- 
gation, in  many  humid  climates,  is  certain  to  be  at- 
tended by  marked  increase  in  the  yield. 


FREQUENCY  AND  LENGTH  OF  PERIODS  OF 
DROUGHT 

In  humid  and  sub-humid  regions,  it  is  the  frequent  recur- 
rence of  periods  of  small  or  no  rainfall,  especially  if  they  occur 
at  the  time  when  the  crop  is  approaching  or  has  reached  the 
fruiting  stage,  that,  more  than  anything  else,  makes  extremely 
careful  and  thorough  tillage,  or  else  supplementary  irrigation, 
indispensable,  if  large  yields  are  to  be  realized. 

In  our  repeated  trials  in  the  field  cylinders  here  in  Wiscon- 


Frequency  and  Length  of  Drought  107 

sin,  we  have  found  it  necessary  to  water  all  of  the  crops  grown 
in  them  as  often  as  once  in  seven  days;  and  even  this  period  has 
been  found  too  long  for  the  soils  which  are  coarse  and  sandy. 
So,  too,  in  our  field  irrigation  we  have  found  that  as  much  as  2 
inches  of  water  may  be  applied  to  corn,  cabbages  and  potatoes  as 
often  as  once  in  10  days,  with  decided  advantage  unless,  in  the 
interval,  there  has  been  a  rain  of  from  .5  to  a  full  inch,  falling 
nearly  at  one  time,  so  as  to  penetrate  the  ground  deeply.  To 
what  extent  and  to  what  advantage  tillage  may  take  the  place  of 
irrigation,  or  make  it  undesirable,  we  shall  discuss  in  the  next 
chapter.  Starting  with  the  soil  well  supplied  with  moisture  at 
seeding  time,  and  then  a  uniform  distribution  of  rains  equal  to  1 
inch  once  in  seven  days  through  the  growing  season,  we  shall  have 
all  the  moisture  that  would  be  needed  for  very  large  crops.  On 
the  average  of  years  most  parts  of  the  United  States  east  of  the 
97th  meridian  have  this  amount  of  rain  during  the  growing  season. 
It  is  true,  however,  that  in  many  parts  of  the  humid  districts  the 
distribution  of  the  rainfall  in  time  and  in  quantity  ie  such  as  to 
cause  severe  suffering  from  drought. 

To  show  just  why  it  is  that  in  Wisconsin  the  irrigation  of 
ordinary  farm  crops  does  produce  a  very  marked  increase  in  the 
yield,  we  have  made  a  study  of  the  distribution  of  the  rainfall  at 
Madison  for  the  years  1887  to  1897,  inclusive.  The  results 
are  here  given  in  a  condensed  form,  as  an  illustration  of  the  type 
of  rainfall  conditions  under  which,  in  a  humid  climate,  it  may  be 
desirable  to  irrigate  where  water  privileges  are  such  as  to  permit 
it  to  be  done  cheaply. 

It  is  generally  true  that  a  rain  of  .05  or  even  of  .1  of  an 
inch,  when  it  comes  alone,  separated  by  two  or  three  days 
from  any  other  rain,  benefits  ordinary  farm  crops  but  little  ;  but 
in  order  that  we  shall  not  undervalue  the  rain  which  falls,  we 
have  included  everything,  large  and  small  alike,  and  have  con- 
structed a  table  for  these  years,  1887  to  1897,  which  shows  the 
length  and  number  of  periods  in  each  year  between  April  1  and 
September  30,  when  there  were  consecutive  days  having  a  rain- 
fall whose  sum  did  not  exceed  .05,  .1,  .5,  1,  1.5,  2,  and  2.5 
inches.  The  table  is  given  below : 


108 


Irrigation   and    Drainage 


Table  showing  the  number  of  periods,  and  the  mean  length  of  these  periods,  in  each 
year  when  the  amount  of  rain  is  not  greater  than  that  given  at  the  head  of  the 
respective  columns 

Rainfall     Rainfall     Rainfall    Rainfall      Rainfall    Rainfall     Rainfall 
of  .05  in.      of  .1  in.      of  .5  in.      of  1  in.       of  1.5  in.     of  2  in.       of  2.5  in. 


PI® 

s.s 


.    6 


^  2 


1887 

20 

7 

22 

6 

18 

9 

12 

13 

11 

14 

10 

18 

8 

24 

1888 

27 

5 

25 

6 

22 

8 

15 

12 

11 

15 

8 

21 

6 

31 

1889 

21 

7 

20 

7 

16 

11 

13 

15 

10 

18 

7 

26 

6 

31 

1890 

28 

4 

23 

6 

20 

8 

17 

10 

16 

10 

14 

13 

12 

15 

1891 

20 

8 

20 

8 

15 

12 

11 

15 

8 

22 

7 

26 

5 

36 

1892 

22 

5 

25 

5 

22 

7 

20 

9 

19 

9 

15 

12 

13 

15 

1893 

22 

6 

23 

6 

20 

9 

18 

9 

14 

13 

12 

15 

10 

18 

1894 

20 

7 

18 

7 

16 

9 

15 

12 

13 

14 

9 

14 

9 

20 

1895 

21 

6 

23 

7 

13 

14 

9 

20 

5 

37 

5 

39 

4 

44 

1896 

27 

4 

27 

5 

27 

6 

26 

7 

19 

10 

15 

12 

11 

17 

1897 

28 

5 

28 

5 

19 

9 

15 

13 

11 

17 

8 

23 

6 

31 

Av.  1'g'h 
period 

5.82 

6.18 

9.27 

12.27 

16.27 

19.91 

25.63 

Av.  No. 
periods 

23.27 

23.09 

18.91 

15.55 

12.45 

1(1 

8.17 

Studying  this  table,  it  will  be  seen  that  during  the  eleven 
years  there  have  been  on  the  average  in  the  growing  season  23 
periods  of  5.82  days'  duration  when  the  rainfall  has  not  exceeded 
.05  inches  ;  there  have  been  23  periods  6  days  long,  with  a  rain- 
fall of  .1  inch  ;  19  periods  on  the  average  9  days  long,  with  a 
rainfall  of  .5  inch  ;  15  periods  each  year  12  days  long,  with  1 
inch  ;  12  periods  16  days  each,  with  but  1.5  inches  ;  10  periods 
each  season  19  days  long,  with  2  inches,  and  8  periods  each 
season  of  25  days  each,  when  the  mean  rainfall  did  not  exceed 
2.5  inches. 

If  we  will  now  compare  the  field  yields  which  are  produced 
under  these  conditions  of  rainfall,  we  shall  be  better  able  to  see 
how  important  are  the  quantity  and  time  distribution  of  rain.  It 


Frequency   and   Length   of  Drought  109 

is  unfortunate  that  we  are  unable  to  present  closely  comparable 
data  for  more  than  the  years  1894,  '95,  '96  and  '97,  and  even  for 
these  years  only  for  corn.  As  for  other  crops  in  the  different 
years,  they  were  grown  on  different  soils  ;  but  bringing  the  yields 
of  dry  matter  of  maize  per  acre  into  comparison  with  the  rainfall 
conditions  under  which  they  were  produced,  we  shall  have  the 
table  which  follows  : 

Table  showing  the  relation  of  yields  of  dry  matter  per  acre  to  the  quantity  and 
distribution  of  rainfall 

Yield  of  dry 

matter  per  acre     Aggregate  No.  of  inches  of  rainfall 

Year                   Periods                   TONS            .05  .1  .5  1  1.5  2  2.5 

.     /No.  of  rainfall  periods  20  18  16  15  13  9  9 

'     I  Length     "             "  days     ^            7  7  9  12  14  14  20 

/No.  of  21  23  13  9  5  5  4 

I  Length     "                                                 6  7  14  20  37  39  44 

1fiQp    /No.  of       "             "  27  27  27  26  19  15  11 

'     I  Length 4'                4  5  6  7  10  12  17 

1BQ_    /No.' of       "             "  28  28  19  15  11  8  6 

1897    \  Length     "            "      "        3'4°5           5  5  9  13  17  23  31 

If  the  rainfall  in  1896  and  in  1894  is  compared  with  that  in 
1895,  when  there  was  a  very  much  smaller  crop,  it  will  be  seen 
that  the  number  of  rainfall  periods  in  1895  is  decidedly  less,  while 
the  length  of  them  is  much  greater.  It  was  this  much  longer 
interval  of  time  intervening  between  like  quantities  of  rain  which 
determined  the  small  yield  ;  and  it  is  this  character  of  the  rain 
of  humid  climates  which  so  seriously  cuts  down  the  average 
yields  per  acre,  and  which  makes  it  possible  for  the  methods  of 
irrigation  to  give  such  constant  and  such  large  yields  wherever  it 
is  well  practiced  in  arid  climates. 

Taking  the  best  year  of  the  four,  1896,  it  will  be  seen  that 
the  average  length  of  periods  of  1  inch  of  rainfall  was  7  days, 
and  there  were  26  of  them  in  the  six  months,  making  about  as 
uniform  distribution  of  rain  as  is  likely  to  occur  in  humid  cli- 
mates ;  but  there  were  in  this  season  1  period  of  10  days,  3 
periods  of  11  days,  2  periods  of  12  days  and  2  periods  of  13  days' 
duration  with  but  1  inch  of  rain,  which  are  too  long  in  Wisconsin 


110  Irrigation    and    Drainage 

to  permit  the  largest  crops  the  soil  is  capable  of  carrying.  This 
statement  is  founded  upon  the  fact  that  with  plenty  of  water  the 
same  soils  did  produce  much  larger  crops,  the  differences  being 
such  as  are  given  in  the  table  below: 

Table  showing  differences  in  yield  when  the  natural    rainfall  in  Wisconsin  is 
supplemented  by  irrigation 


-Yields  per  acre- 


Corn            Potatoes      Strawberries  Cabbage  Barley            Clover 

•8            •  1               "S  "2  "S              ^ 

-     S    -     s    *     I  *    I  i    I 

-§          £  %         fc  5         £ 


8          fc  o          '£  o  g  o  g  o          g  o  go 

TONS  TONS  BU.         BU.  BOXES  BOXES  TONS    TONS      BU.        BU.       TONS  TONS 

1894  5.176  3.835  6,867    3,496     

1895  5.293  1.384  8,732    1,030     51         25         4.01      1.45 

1896  5.15  4.145  394.2    290.5      22.79    20.04      3.632    2.254 

1897  4.252  3.405  333.9    212.3      45.67    44.25   4.434    2.482 

These  figures  show  very  clearly  the  insufficiency  of  rain  in 
these  four  years  to  produce  the  largest  possible  yields,  and  they 
show  to  what  extent  irrigation  in  a  climate  such  as  that  which 
has  occurred  during  the  years  1894  to  1897  in  Wisconsin  is  likely 
to  increase  the  average  yields. 


CONDITIONS   WHICH    MODIFY  THE    EFFECTIVENESS    OF 
RAINFALL 

The  rains  which  fall  upon  a  given  area  are  not  equally  effec- 
tive under  all  conditions  of  soil  and  topography,  and  hence  it 
happens  that  irrigation  may  be  desirable  in  localities  where  the 
amount  of  rain  which  falls  may  be  both  large  and  uniformly  dis- 
tributed throughout  the  growing  season.  It  has  been  pointed  out, 
in  the  study  aiming  to  measure  the  amount  of  water  required  to 
produce  a  pound  of  dry  matter,  that  it  was  necessary  to  water  the 
sandy  soils  of  coarse  texture  once  in  three  to  four  days  in  order 


Conditions  Modifying  Effectiveness  of  Rainfall  111 

to  prevent  the  crops  from  suffering  for  lack  of  moisture,  while 
once  in  seven  days  met  the  needs  of  plants  growing  upon  soils 
of  the  finer  texture  used  in  the  experiments. 

The  difficulty  in  the  case  of  soils  of  coarse  texture  is,  not 
that  the  water  evaporates  more  rapidly  from  the  surface  of  them, 
nor  is  it  because  more  water  must  be  present  in  them  in  order 
that  plants  may  utilize  it,  for  it  is  true  that  the  surface  evapora- 
tion from  them  is  slower  than  with  most  other  soils,  and  that 
plants  may  use  the  water  more  closely  from  them  than  is 
possible  when  the  grains  are  smaller.  The  real  trouble  is  found 
in  the  fact  that  when  they  are  underlaid  by  a  coarse  subsoil,  and 
when  standing  water  in  the  ground  is  more  than  5  feet  below 
the  surface,  the  water  drains  out  so  completely  in  a  short  time 
that  not  enough  remains  to  keep  the  crop  from  wilting. 

We  do  not  yet  know  how  closely  the  water  may  be  used  up 
in  field  soils  of  different  textures  before  crops  of  different  kinds 
will  begin  to  suffer,  or  will  have  their  rate  of  growth  checked  ; 
but  the  writer  has  found  that  clover,  timothy,  blue -grass  and 
maize  have  their  growth  brought  nearly  to  a  standstill  in  a  clay 
loam  soil  underlaid  with  sand  at  3  to  4  feet,  when  the  amount  of 
water  left  in  it  was  that  stated  in  the  table  below: 

Table  showing  the  amount  of  water  in  a  clay  loam  in  the  field  when  crops  wilted 
and  growth  was  brought  nearly  to  a  standstill 

Timothy  and 

Clover  Blue-grass  Maize 

Depth  of  sample                       PKB  CENT  PER  CENT  PER  CENT 

0-  6  inches  loam                                  8.39  6.55  6.97 

6-12       "       clay  loam                         8.48  7.62  7.8 

12-18       "       clay                                  12.42  11.49  11.6 

18-24       "       clay                                  13.27  13.58  11.98 

24-30       "       clay                                  13.52  13.26  10.84 

40-43       "       sand                                  9.53  18.37  4.17 

Nothing  more  definite  can  be  said  regarding  the  data  of  this 
table,  than  that  under  the  moisture  relations  there  shown,  growth 
was  practically  at  a  standstill,  and  that  when  very  considerably 
larger  percentages  of  water  were  present  in  the  soil  the  normal 
rate  of  growth  was  checked.  . 


112 


Irrigation   and    Drainage 


How  completely  water  will  drain  out  of  sands  by  percolation 
under  conditions  in  which  almost  no  evaporation  can  take  place,  is 
shown  by  the  data  in  the  table  which  follows,  in  which  the  results 
were  obtained  by  a  set  of  apparatus  shown  in  Fig.  21.  It  will  be 


nSnnin  rsi  rainln 


Fig.  2L    Method  of  determining  water-holding  power  of  long  columns  of  sand. 

seen  that  the  conditions  provided  by  the  apparatus  are  such  that 
standing  water  was  maintained  continuously  in  the  soil  at  a  level 
of  8  feet  below  the  surface,  and,  hence,  that  the  amount  of  water 
retained  in  the  whole  column  was  much  greater  than  it  would 
have  been  were  it  under  such  field  conditions  as  when  standing 


Water  Lost    by    Percolation  113 

water  in  the  ground  is  found  at  greater  distances  below  the  sur- 
face: 

Table  showing  the  per  cent  of  water  in  8-foot  columns  of  sand  after  percolation 
periods  of  different  lengths 

Effective  diameter  of  sand 

grains 474  mm.     .185  mm.     .155  mm.     .1143  mm.  .0826  mm. 

Height  of  sec'n 
above  ground 

water  Water  retained  after  percolating  over  2  years 

INCHES          FEET          PER  CENT       PEE  CENT  PER  CENT       PER  CENT  PER  CENT 

96  ....  93  .27  .17  .22                 1.26  3.44 

93  ....  90  .22  .17  .23                 1.16  3.44 

90  ....  87  .23  .16  .29                 1.34  3.82 

87  ....  84  .22  .15  .32                 1.61  3.83 

84  ....  81  .23  .18  .61                 1.98  3.93 

81  ....  78  .29  .19  1.07                 2.32  4.19 

78  ....  75  .44  .26  1.33                 2.61  4.38 

75  ....  72  .89  .58  1.57                 2.90  4.92 

72....  69  1.18  1.16  1.80                 3.12  4.94 

69....  66  1.48  1.45  1.85                 3.36  5.70 

66....  63  1.71  1.67  2.03                 3.56  5.91 

63  ....  60  1.80  1.80  2.18                 3.92  6.43 

60  ....  57  1.83  1.86  2.26                 4.22  6.77 

57....  54  1.93  1.87  2.27                 4.53  7.72 

54....  51  1.98  1.98  2.30                 4.88  8.59 

51  ....  48  2.02  1.92  2.38                 5.42  9.42 

48  ....  45  2.03  2.12  2.46                 6.03  10.50 

45  ....  42  2.02  2.07  2.71  6.99  11.34 

42  ....  39  2.06  2.18  3.08                 7.47  12.58 

39  ....  36  2.17  2.29  3.46.                 8.71  13 

36....  33  2.31  2.48  4.10  10.54  14.95 

33  ....  30  2.36  2.65  5.09  11.77  15.90 

30....  27  2.63  3.14  6.36  12.95  17.20 

27  ....  24  2.86  3.63  8.74  15.05  17.96 

24  ....  21  3.42  4.71  13.52  17.24  18.92 

21  ....  18  4.26  6.76  23.57  19.08  20.49 

18  ....  15  6.41  9.38  27.93  19.37  21.34 

15  ....  12  9.77  14.66  23.61  21.44  21.63 

12  ....    9  16.08  21.31  22.46  22.69  22.68 

9  ....    6  19.33  22.39  22  76  23.20  23.39 

6  ....    3  20.96  23  52  22.88  24.22  30  28 

3  .....    0  21.58  24.61  23.54  25.07  24.06 


114  Irrigation   and    Drainage 

,          Jgms.          2,1214       2,474.9       3,515.         4,576.2       5,831.5 
Total  water  retained....  |  percent        -^  &  Q5  ?  25          g  41         n  g2 

Water  retained  after  4 /gins.  3,128.  3,551.1  4,259.9  5,672.  6,659.7 

days I  per  cent  6.25  7.238  8.785  11.66  13.5 

Water  retained  after  9 /gins.  2,926.  3,213.5  4,094.7  5,416.2  6,452.8 

days I  per  cent  5.846  6.753  8.445  11.13  13.08 

fgms.        10,425.2     10,356.2     10,329.1     10,289.7     10,606.8 
Total  waterrecovered...|percent        ^         ^         2O  ^         21<g 

Total  weight  of  dry  sand... gms.        50,050.       49,060.       48,490.       48,650.       49,340. 

A  glance  at  this  table  shows  how  completely  and  how  rapidly 
water  will  drain  away  by  downward  percolation  from  the  coarse 
and  fine  sands  when  there  is  nothing  within  8  feet  of  the  surface 
to  prevent  it.  It  will  be  seen  that  in  four  days  the  coarsest  sand 
had  lost  nearly  three-quarters  of  all  the  water  it  could  contain 
under  flooded  conditions,  while  the  finest  had  lost  nearly  one- 
half  ;  and  this  has  occurred,  too,  under  such  conditions  that 
standing  water  is  maintained  within  8  feet  of  the  surface.  Had 
standing  water  been  16  feet  from  the  surface,  it  is  quite  likely 
that  the  surface  8  feet  of  these  sands  would  not  have  retained  3 
per  cent  in  the  coarsest  sample  nor  5  per  cent  in  the  finest. 

With  such  a  rate  of  loss  of  water  from  sands  as  this,  it  must 
be  plain  that  the  coarser  soils,  when  they  are  long  distances  from 
standing  water  in  the  ground,  or  are  not  underlaid  with  a  more 
impervious  stratum  near  the  surface,  must  lose  the  water  which 
falls  upon  them  as  rain  so  rapidly  that  even  in  very  humid  regions 
they  cannot  maintain  profitable  crops  without  irrigation. 

It  is  this  fact  of  coarse  texture,  coupled  with  the  long  inter- 
vals of  deficient  rain,  more  than  a  lack  of  plant-food,  which  has 
maintained  in  an  unproductive  state  the  extensive  areas  of  sandy 
lands  found  in  Minnesota,  Wisconsin,  Michigan,  New  York,  New 
Jersey,  and  further  south,  in  the  United  states,  and  throughout 
Belgium,  Holland,  and  the  plains  of  northern  Germany,  in 
Europe.  Had  the  soils  of  these  areas  identically  the  same 
chemical  composition,  but  a  texture  as  fine  as  that  of  our  best 
soils,  so  that  water  would  drain  from  them  no  more  rapidly, 
profitable  agriculture  could  be  practiced  upon  them  tinder  the 
rainfall  conditions  which  exist.  And  it  is  possible  to  so  supple- 


Water   Lost   by   Surface   Drainage  115 

ment  the  rainfall  upon  these  types  of  land  by  irrigation  as,  even 
with  the  coarse  texture  they  have,  to  make  them  bear  remuner- 
ative crops  of  various  kinds,  as  has  been  abundantly  proved  in 
many  places. 

Passing  from  the  extreme  type  of  "barrens"  soil  which  we 
have  been  discussing,  there  are  extremely  large  areas  of  only  the 
less  coarse  loamy  sands  and  sandy  loams  in  all  humid  climates, 
where  supplementary  irrigation,  could  it  be  practiced,  would 
greatly  increase  the  average  yields  beyond  the  largest  which  are 
possible  with  the  best  of  tillage  ;  but  the  truth  of  this  proposition 
does  not  carry  with  it  the  corollary  that  it  will  pay  to  irrigate 
them  whenever  there  is  an  abundance  of  water  to  do  so. 

Then,  there  are  topographic  conditions  which  greatly  diminish 
the  effectiveness  of  the  rain  which  may  fall  in  a  given  locality. 
When  the  fields  are  decidedly  rolling,  every  one  is  familiar  with 
the  fact  that  wherever  heavy  rains  occur  in  short  periods  of  time 
very  considerable  percentages  of  such  rains  flow  at  once  over  the 
surface  to  the  lower  lying  lands,  producing  only  damaging  effects 
upon  the  hillsides.  Under  such  conditions,  it  is  plain  that  the 
measured  rainfall  of  the  growing  season  is  not  available  for  crop 
production,  even  though  the  texture  of  the  soil  were  such  as  to 
retain  the  whole  of  it,  could  it  rest  upon  the  surface  long  enough 
to  be  absorbed.  Further  than  this,  the  brows  of  hills,  where 
they  are  exposed  to  the  prevailing  winds,  lose  a  much  higher 
percentage  of  the  absorbed  soil  moisture  by  surface  evaporation  than 
is  the  case  on  the  level  plains  or  in  the  sheltered  valleys,  and 
from  this  it  follows  that  when  the  whole  rainfall  of  the  growing 
season  is  only  enough  to  make  the  soil  produce  at  its  full 
capacity,  the  exposed  hillsides  must  receive  irrigation  sufficient 
to  make  good  the  losses  by  surface  drainage  and  greater  evapo- 
ration, if  equally  large  yields  per  acre  are  expected. 

Again,  in  rolling  countries,  where  the  higher  lands  are 
porous,  the  rains  which  are  there  lost  by  deep  percolation  reap- 
pear under  the  lower  lands,  to  supplement  the  rain  which  falls 
directly  there,  and  often  to  such  an  extent  as  to  make  under- 
draining  a  necessity.  Where  these  conditions  exist,  and  where 
drainage  is  sufficient,  so  that  crops  may  take  advantage  of  the 


116  Irrigation    and    Drainage 

underflow  which  gives  rise  to  a  natural  sub -irrigation,  it  is  evi- 
dent that  on  such  lands  a  much  smaller  rainfall,  and  even  longer 
intervals  between  rains,  may  occur  without  producing  suffering 
from  drought. 

From  what  has  been  shown  regarding  the  amount  of  water 
used  by  different  crops  in  coming  to  maturity,  it  is  plain  that 
with  a  full  command  of  water  for  irrigation,  it  would  be  possible 
for  crops  to  be  grown  on  a  given  soil  in  a  given  locality  when  the 
natural  rainfall  would  not  permit  that  crop  to  be  so  grown.  It 
is  plain,  therefore,  that  neither  the  amount  of  rain  nor  the  dis- 
tribution of  it  are  sufficient  to  determine  under  what  conditions 
irrigation  will  or  will  not  pay. 


CHAPTER    III 

THE  EXTENT  TO    WEIGH  TILLAGE  MAT  TAKE   THE 
PLACE   OF  RAIN  OR   IRRIGATION 

WERE  it  desirable  to  irrigate  all  agricultural  lands 
lying  in  humid  climates,  it  would  not  be  possible  to 
do  so,  on  account  of  the  insufficiency  of  water  for  the 
purpose.  The  truth  of  this  proposition  will  be  evident 
if  we  deal  quantitatively  with  the  problem. 

THE     INSUFFICIENCY    OF    WATER     TO     IRRIGATE     ALL 
CULTIVATED    LANDS 

Humphreys  and  Abbott  have  placed  the  mean  an- 
nual discharge  of  the  Mississippi  at  19,500,000,000,000 
cubic  feet,  while  the  catchment  area  is  placed  at  1,- 
244,000  square  miles.  Assuming  that  these  quantities 
are  correct,  then  the  mean  annual  run -off  for  the 
whole  Mississippi  basin  would  be  6.747  inches.  But 
not  all  this  run -off  is  available  for  irrigation,  were  it 
desirable  to  so  use  it ;  for  during  a  large  part  of  the 
time  this  water  is  flowing  away  when  the  season  does 
not  permit  of  its  being  used,  and  it  is  impracticable  to 
impound  it  and  hold  it  until  it  might  be  used.  If  we 
take  the  mean  daily  discharge  of  the  river  as  TBT  of 
its  annual  amount,  and  allow  that  the  whole  of  this  is 

(117) 


118  Irrigation   and    Drainage 

available  for  irrigation  purposes  during  the  irrigation 
season,  it  is  capable  of  watering  but  .092  of  the  catch- 
ment area  at  the  rate  of  2  inches  of  water  once  in  10 
days. 

It  is  true  that  the  mean  run -off  for  the  whole 
basin  is  less  than  is  found  in  much  of  the  United 
States  ;  but,  taking  a  district  where  the  mean  drainage 
to  the  sea  is  30  inches  instead  of  6.7,  and  supposing 
that  this  is  collected  into  canals,  so  as  to  be  used  for 
irrigation,  then  it  would  be  able  to  supply  only  about 
.4  of  the  area  at  the  rate  assumed  above.  It  is 
safe  to  say  that  these  estimates  of  the  area  which 
might  be  irrigated  with  such  amounts  of  water  is  too 
large,  for  the  summer  discharge,  when  irrigation,  is 
needed,  is  in  most  drainage  basins  much  less  than 
the  mean  values  which  have  been  taken  in  making 
the  calculations. 

Newell  has  made  as  close  an  estimate  of  the  mean 
annual  run -off  for  the  United  States  as  the  then  ex- 
isting data  would  permit,  and  has  expressed  the 
results  in  a  map,  which  is  reproduced  in  Fig.  22.  An 
inspection  of  this  map  will  make  it  plain,  in  connec- 
tion with  what  has  been  said,  that  however  great  irri- 
gation developments  may  become  in  the  future,  it  is 
not  possible  for  the  practice  to  be  extended  so  as  to 
displace  the  methods  of  "dry  farming."  Hence  the 
question,  How  far  may  tillage  compensate  for  a  defi- 
cient rainfall?  will  long  remain  a  pertinent  one  in 
agricultural  practice. 

Since  much  less  than  one -half  of  agricultural  lands 
can  be  irrigated  under  any  efforts  which  can  be  made, 


120  Irrigation   and    Drainage 

it  is  plain  that  the  question,  What  are  the  largest 
possible  yields  which  may  be  realized  without  irri- 
gation ?  is  of  much  greater  practical  moment  than  its 
converse. 


THE    MOST    WHICH    MAY    BE     HOPED    FOB    TILLAGE 
IN    THE    USE     OF    WATER 

We  have,  as  yet,  been  unable  experimentally  to 
demonstrate  that  any  method  of  handling  the  soil 
under  field  conditions  will  permit  it  to  abstract  from 
the  air  above  it  an  amount  of  moisture  sufficiently 
large  to  materially  contribute  to  the  supply  already  in 
the  soil,  and  thus  aid  in  compensating  for  a  deficient 
rainfall.  The  discussion  presented  on  a  preceding 
page,  regarding  the  production  of  wheat  in  California 
and  Washington  without  irrigation,  certainly  lends  no 
weight  to  the  view  that  the  hygroscopic  power  of  soils 
aids  in  supplying  moisture  to  the  crops  under  field 
conditions.  Still,  it  must  be  admitted  that  those  who 
maintain  that  soils  do  absorb  important  quantities  of 
moisture  from  the  air  direct  may  continue  to  do  so 
without  fear  of  successful  refutation  by  existing  posi- 
tive knowledge. 

If  it  is  true  that  soils  do  not  withdraw  from  the 
air  important  quantities  of  water,  then  the  most  which 
can  be  hoped  for  by  methods  of  tillage  is  that  they 
may  store  in  the  soil  and  retain  there  the  water  which 
falls  as  rain,  until  that  shall  be  removed  by  the  action 
of  the  roots  of  the  crop  growing  upon  the  field.  Cer- 
tain it  is  that  no  method  of  tillage  now  practiced  can 


Amount   of  Rain   Needed  121 

very  much  increase  the  moisture  in  the  soil  above  that 
which  falls  as  rain  or  snow. 

Further  than  this,  we  have  no  reason  to  believe 
that  mere  tillage,  as  such,  can  in  any  way  diminish 
the  rate  of  transpiration  from  the  crop  which  is  grow- 
ing upon  the  soil  being  tilled,  unless,  indeed,  it  should 
be  done  by  root -pruning,  a  method  decidedly  injurious 
in  most  cases.  It  follows,  therefore,  that  in  no  way 
can  we  hope,  by  methods  of  tillage,  to  diminish  the 
loss  of  water  by  transpiration  through  the  crop  itself. 
We  may,  indeed,  make  the  conditions  for  growth  so 
favorable  that  the  maximum  amount  of  dry  matter  is 
developed  during  the  time  a  given  amount  of  water 
is  being  evaporated  from  the  surface  of  the  crop ;  but 
so  far  as  the  direct  influence  of  tillage  is  concerned,  it 
can  only  lessen  the  evaporation  from  the  soil  surface, 
and  reduce  the  losses  by  percolation  and  by  surface 
drainage.  No  amount  or  kind  of  tillage  can  dispense 
with  water ;  that  must  be  had,  either  from  rain  or 
snow,  or  be  supplied  by  irrigation.  With  water  enough 
in  the  soil  to  make  a  crop,  good  tillage  will  bring  the 
most  out  of  it ;  but  when  the  rainfall  has  really  been 
deficient,  noth'ng  short  of  irrigation  can  make  the  crop. 


AMOUNT     OF     RAIN     NEEDED     TO     PRODUCE     CROPS 
IN    HUMID    AND    SUB -HUMID    REGIONS 

Having  pointed  out  in  a  general  way  the  limitations  of  tillage 
in  conserving  soil  moisture  for  crop  production,  it  is  important  to 
show  how  great  its  possibilities  may  be  when  unaided  by  irriga- 
tion ;  for  if  in  humid  and  sub-humid  climates  tillage  may  enable 


122  Irrigation   and    Drainage 

all  soils  to  produce  maximum  crops  of  all  kinds,  then  irrigation 
will  be  unnecessary  in  them. 

It  has  been  shown  that,  under  conditions  in  which  no  water 
can  be  lost  by  surface  or  under-drainage: 

Clover  uses  5.089  acre-inches  in  producing  one  ton  of  dry  matter. 
Oats         "     4.447 
Barley      "     4.096 
Maize        "      2.391 
Potatoes  use  3.399 

These  figures  are  an  approximate  measure  of  the  demands  of 
those  crops  for  water,  and  if  one,  two  or  three  tons  of  dry  matter 
per  acre  are  to  be  produced  by  these  crops,  then  the  amount  of 
available  rainfall  needed  will  be  given  by  multiplying  the  figures 
in  this  table  by  the  yield  which  is  expected  per  acre  from 
the  soil. 

Let  us  see  what  the  available  rainfall  is  in  various  parts  of 
the  eastern  and  central  United  States.  To  make  the  discussion  as 
pointed  as  possible,  let  us  draw  our  data  from  the  states  of  Illi- 
nois, Indiana,  Iowa,  eastern  Kansas,  Maine,  Michigan,  Missouri, 
Minnesota,  New  York,  Ohio,  Pennsylvania,  Vermont,  and  Wiscon- 
sin. In  these  states,  what  is  the  amount  of  rainfall  available  for 
crop  production  ? 

In  the  map,  Fig.  23,  is  represented  the  mean  annual  rainfall  of 
the  United  States,  as  given  by  the  Weather  Bureau.  Such  a  map, 
however,  does  not  show  the  amount  of  water  which  is  available  for 
crop  production,  because,  as  shown  on  the  map,  Fig.  22,  a  large 
part  of  this  rain  is  carried  to  the  sea  in  the  rivers,  and  cannot, 
therefore,  be  used  in  producing  crops.  But  if  the  rains  which 
would  drain  away  were  subtracted  from  the  mean  annual  rainfall, 
the  difference  would  still  be  too  large,  for  we  have  many  showers 
which  are  too  slight  to  be  of  any  service  whatever.  Not  only  this, 
but  very  light  rains  often  do  positive  injury  by  destroying  the 
effectiveness  of  earth  mulches  which  have  been  developed  by  till- 
age, thus  causing  a  loss  of  a  part  of  the  water  already  in  the  soil, 
with  that  which  fell  as  rain. 

It  is  further  necessary,  in  discussing  this  problem,  to  consider 


124  Irrigation   and    Drainage 

the  growing  season  of  the  specific  crop  in  question,  in  order  to 
know  whether  tillage  alone  will  answer  for  that  crop,  unaided  by 
irrigation.  The  first  crop  of  clover,  for  example,  must  be  largely 
made  by  the  rains  of  May  and  June  in  the  states  which  have  been 
named,  while  the  crop  of  potatoes  will  be  determined  more  largely 
by  that  which  falls  between  June  and  October.  The  period  of 
barley  would  extend  from  May  1  nearly  through  July  ;  oats,  from 
May  to  the  middle  of  August  ;  and  maize,  from  the  middle  of  May 
to  the  middle  of  September. 

In  the  table  which  follows,  the  amount  of  rain  which  falls 
during  the  growing  season  of  barley,  oats  and  maize  has  been 
given,  and  from  the  averages  have  been  deducted  the  amounts 
which  it  is  quite  certain  do  not  become  available  for  crop  produc- 
tion, on  account  of  loss  by  drainage  and  by  the  light  rains  not 
penetrating  deeply  enough  to  be  of  service  agriculturally: 

Table  showing  the  mean  rainfall  for  the  growing  season  for  barley,  oats 

and  maize  Rainfall  in  inches  for 

Barley  Oats  Maize 

niinois 13  15  15.25 

Indiana  . . . ., 13.5  15.25  16.25 

Iowa 12.5  14.25  15.375 

Eastern  Kansas 12  13.625      14.5 

Southern  Maine 10.5  12.25  14 

Southern  Michigan 9.5  11  12.625 

Missouri 13.25  15  16.375 

Minnesota 10.75  12.25  13.75 

New  York 10.25  12  13.5 

Ohio 11.75  13.5  15 

Pennsylvania 12  14  15.75 

Vermont 10.5  12.5  14.75 

Wisconsin 11.5  13.25  15 


Mean 11.616      13;375      14.779 

Estimated  loss  by  percolation  and  from  light  showers.         2.964       3.185       2.765 
Mean  effective  rain 8.652      10.19        12.014 

In  estimating  the  loss  from  percolation  and  small  showers,  2 
inches  has  been  assumed  as  the  amount  of  percolation  in  the  case 
of  barley  and  oats,  and  1.5  inches  for  maize.  The  amount  deducted 
for  small,  ineffective  showers  has  been  gotten  by  taking  the  total 


Time   Distribution   of  Rain  125 

rainfall  for  Madison,  Wisconsin,  from  1887  to  1897,  which  was 
less  than  .2  of  an  inch  in  any  day  of  24  hours  during  the  periods 
covered  by  the  table. 

Now,  these  amounts  of  effective  rain,  could  they  be  used  with 
the  same  economy  as  we  were  able  to  use  them  in  our  plant  cylin- 
ders, ought  to  produce  the  following  yields  per  acre: 

Bu.  per  acre 

Barley 40.29 

Oats 64.97 

Maize 71.51 

In  making  these  calculations,  the  ratio  of  grain  to  straw  for 
barley  has  been  taken  as  2  to  3,  and  for  oats  as  1  to  1.448;    and 
we  have  used  the  percentages  of  water  in  grain  and  straw  given  in  . 
tables  of  feeding -stuffs.     In  the  case  of  maize,  data  derived  from 
direct  determinations  by  the  writer  have  been  used. 

It  will  be  seen  that  these  computed  yields,  although  much 
larger  than  average  yields,  are,  nevertheless,  very  close  to  what  is 
expected  during  our  best  seasons,  when  there  has  been  plenty  of 
rain,  well  distributed,  and  when  the  crop  has  not  been  affected  by 
disease  or  insects.  It  appears,  therefore,  that  the  rainfall  for  the 
thirteen  states  enumerated  is  sufficient  in  quantity  to  produce  very 
heavy  crops,  not  only  of  the  three  grains  named,  but  of  many 
others  also. 


THE    DISTRIBUTION    OF     EAIN    IN    TIME    USUALLY    UNFA- 
VORABLE   TO    MAXIMUM    YIELDS 

There  is  little  question  that  in  the  thirteeen  states  named,  the 
mean  yields  of  barley,  oats  and  maize  would  easily  be  held  to 
41,  64  and  75  bushels  per  acre  respectively,  if  it  were  only  possible 
to  control  the  distribution  of  rain  in  time  and  in  quantity,  as  it  is 
controlled  by  irrigation.  As  it  is,  however,  such  large  mean 
yields  can  never  be  reached  by  tillage  alone  in  a  territory  as 
extended  as  that  under  consideration.  This  will  be  evident  from 
the  table  which  follows,  in  which  the  mean  pelds  of  barley,  oats 


126  Irrigation   and    Drainage 

and  maize  for  1879  are  given  as  reported  for  the  10th  Census  for 

the  thirteen  states: 

Bu.  barley  Bu.  oats  Bu.  maize 

per  acre  per  acre  per  acre 

Illinois 22.25  32.24  36.12 

Indiana 23.35  25.02  31.39 

Iowa 20.23  33.57  41.57 

Kansas 12.52  18.77  30.93 

Maine 21.81  28.76  30.99 

Michigan 22.1  33.93  35.3 

Missouri  19.01  21.34  36.22 

Minnesota 25.62  37.97  33.81 

New  York 21.85  29.79  32.97 

Ohio 29.7  31.49  34.09 

Pennsylvania 18.57  27.34  33.37 

Vermont 25.36  37.57  36.46 

Wisconsin 24.68  34.43  33.71 

Mean 22.08  30.17  34.38 

If  a  comparison  is  made  between  these  reported  yields  and 
those  which  are  given  above  as  possible  with  the  recorded  rain- 
falls, when  a  favorable  distribution  in  time  occurs,  it  will  be  seen 
that  the  mean  reported  yields  are  only  about  half  as  large  as  the 
computed  ones,  and  as  observed  ones  are  in  localities  where  the 
distribution  of  rain  in  time  and  in  quantity  has  been  favorable. 

These  small  average  yields,  reported  from  so  many  states, 
and  agreeing  so  closely  one  with  another,  must  be  looked  upon 
as  expressing  conditions  unfavorable  to  large  yields,  and  condi- 
tions which  the  best  of  management  cannot  hope  wholly  to 
counteract. 

The  facts  are  that  we  are  here  confronted  with  results  which 
are  due,  in  a  very  large  measure,  to  the  long  intervals  between 
effective  rains,  to  which  reference  has  already  been  made.  This 
uneven  distribution  is  so  general  in  its  character  that  when 
the  yields  over  wide  areas  are  brought  together  for  comparison, 
the  small  yields  due  to  faulty  distribution  of  rain  so  far  outweigh 
the  large  yields,  where  the  amount  of  moisture  has  been  just 
right,  that  small  averages  are  inevitable.  Nor  is  this  condition 
of  things  strange  ;  for,  since  the  rainfall  is  in  no  way  controlled 
by  any  factor  operating  to  cause  precipitation,  either  when  it  is 


Tillage    to    Conserve   Moisture  127 

wanted  or  in  the  amount  which  the  particular  crop  on  the  par- 
ticular soil  may  at  that  time  need,  it  cannot  be  expected  that 
such  a  regime  of  chance  would  on  the  average  develop  the  con- 
ditions most  favorable  to  large  crops. 


THE      METHODS     OF     TILLAGE     TO     CONSERVE     MOISTURE 
ARE    OFTEN    INAPPLICABLE 

If  it  is  urged  that  better  tillage  and  more  systematic  rota- 
tions of  crops,  coupled  with  a  more  rational  practice  of  fertiliza- 
tion of  the  soil,  would  go  a  long  way  toward  making  larger 
average  yields,  every  one  must  admit  the  truth  of  the  assertion. 
But,  while  this  is  true,  it  must  still  be  recognized  that  there  are 
some  cases  in  which  the  methods  of  tillage  to  conserve  soil  mois- 
ture are  either  wholly  inapplicable  or  they  may  be  applied  only 
with  so  great  difficulty  or  with  so  small  an  effect,  that  they  have 
never  come  into  general  use  for  the  specific  purpose  of  saving 
soil  moisture. 

The  most  important  illustration  in  point  is  that  of  the  hay 
crop,  with  which  should  also  be  associated  that  of  pasture  as 
well,  when  these  are  made  from  the  grasses  and  from  clover. 
With  these  two  crops,  hay  and  pasture;  which  together  cover  a 
wider  acreage  than  any  other  single  crop  grown,  there  has  not 
been  and  cannot  well  be  any  method  of  tillage  aiming  specifically 
to  conserve  soil  moisture  for  the  use  of  the  crop. 

In  the  thirteen  states  referred  to  when  discussing  the  yields 
of  barley,  oats  and  maize,  there  were  cut  24,439,485  acres  of 
grass,  making  28,314,650  tons  of  hay,  or  at  the  mean  rate  of 
1.158  tons  per  acre,  in  1879.  Nearly  all  of  this  hay  is  made 
during  the  months  of  May  and  June,  when  there  is  a  mean  rain- 
fall for  the  thirteen  states  amounting  to  7.83  inches,  of  which 
not  less  than  2  inches  is  lost  by  percolation,  and  nearly  .69  of  an 
inch  is  ineffective  on  account  of  showers  giving  less  than  .2  of 
an  inch,  thus  leaving  an  effective  rain  of  5.14  inches 

It  has  been  shown  that  clover  uses  5.089  acre -inches  of  water 
in  producing  one  ton  of  dry  matter,  and  at  this  rate  5.14  inches 


128  Irrigation   and    Drainage 

of  effective  raiu  ought  to  give  a  yield  of  1.01  tons  of  dry  matter  ^ 
equal  to  1.188  tons  of  hay  containing  15  per  cent  of  water,  while 
the  observed  mean  yield  is  1.158  tons.  Now,  this  yield  of  1.1 
tons  per  acre  is  not  what  a  farmer  calls  a  good  yield,  for  1.5 
tons  to  2  tons  per  acre  of  hay  are  often  cut  ;  but  these  larger 
yields  are  invariably  associated  with  seasons  of  early  heavy  rain- 
fall. It  must  be  evident,  then,  that  in  the  thirteen  states  from 
Maine  to  eastern  Kansas  there  are  large  areas  where,  if  water 
could  be  applied  to  the  first  crop  of  hay,  the  yield  might  easily 
be  increased  40  to  90  per  cent,  and  there  can  be  no  question 
that  the  aggregate  extent  of  such  areas  exceeds  what  could  be 
supplied  by  all  the  water  of  all  the  rivers  and  all  the  ground 
water  of  those  states. 

Then,  again,  in  the  case  of  such  crops  as  wheat,  oats,  barley, 
rye,  buckwheat,  and  the  millets,  which  are  sown  broadcast  or  in 
close  drills,  it  has  not  been  usual  to  practice  methods  of  tillage 
aiming  specifically  to  save  moisture  ;  but  when  the  acreage  of 
these  crops  in  the  United  States,  together  with  that  of  hay  and 
pasture,  is  set  aside,  there  remains  relatively  but  a  small  part 
of  the  cultivated  lands  upon  which  intertillage  is  or  can  well  be 
practiced. 

These  statements  are  made  neither  to  depreciate  the  impor- 
tance of  conserving  soil  moisture  by  tillage  nor  to  emphasize  the 
importance  of  irrigation,  but  rather  that  each  may  be  seen  in  its 
true  perspective  ;  for  the  fact  is,  neither  method  is  universally 
adapted  to  meet  the  needs  of  insufficient  rain  at  all  times  and  in 
all  places.  But  there  are  conditions  for  which  each  is  better 
suited  than  the  other,  and  for  a  man  to  know  these  is  to  make 
him  a  better  farmer. 

TILLAGE     TO      CONSERVE      SOIL     MOISTURE      IS      CHIEFLY 

EFFECTIVE    IN     SAVING    THE    WINTER    AND 

EARLY    SPRING    RAINS 

It  is  not  sufficiently  appreciated  that  early  and  frequent  till- 
age where  irrigation  is  not  practiced  is  far  more  important  and 
effective  in  conserving  soil  moisture  than  later  tillage  can  be 
after  the  ground  once  becomes  dry.  From  this  it  follows  that 


Tillage   to    Conserve   Moisture  129 

intertillage  and  surface  tillage  generally  can  be  counted  upon  as 
capable  of  saving  to  the  crop  which  is  to  be  grown  upon  the 
ground  only  a  part  of  the  rains  which  fall  in  winter  and  spring. 
The  rains  of  later  June  and  July,  August  and  September  are 
usually  beyond  the  power  of  tillage  to  conserve  in  any  marked 
degree,  without  at  the  same  time  seriously  injuring  the  roots  of 
vegetation  growing  upon  the  ground. 

In  the  first  place,  after  the  last  of  June,  in  climates  like 
that  of  the  thirteen  states  selected,  the  water  of  nearly  all  rains 
is  absorbed  and  retained  in  the  surface  3  inches  of  soil  or  less. 
It  is  only  the  rains  exceeding  1  inch  which  penetrate  more  deeply 
than  this  ;  and  to  stir  a  wet  soil  is  to  hasten  the  rate  of  evapora- 
tion of  moisture  from  the  soil  stirred.  If,  then,  the  roots  of  a 
crop  have  dried  the  surface  8  inches  of  soil  so  that  it  contains 
but  20  to  30  per  cent  of  its  full  amount,  and  a  rain  falls  which 
wets  in  but  2  inches,  stirring  that  soil  can  save  but  little  of  the 
moisture.  Further  than  this,  when  the  surface  of  the  soil  has 
become  so  dry,  capillarity  acts  very  slowly  to  conduct  the  water 
downward  into  the  soil. 

In  the  second  place,  most  cultivated  crops,  in  order  to  take 
advantage  of  the  general  fact  that  summer  rains  do  not  as  a  rule 
penetrate  deeply  into  the  soil,  develop  a  system  of  roots  ex- 
tremely close  to  the  surface  of  the  ground,  where  momentary  ad- 
vantage may  be  taken  of  those  rains  which  do  not  wet  in  deeply  ; 
and  hence  it  is  that  in  sub-humid  climates,  and  after  a  dry  time 
in  all  climates,  surface  cultivation  right  after  a  rain  may  do  posi- 
tive injury  by  cutting  off  roots  which  have  been  developed  to 
take  advantage  of  such  rains,  while  at  the  same  time  the  rate 
of  evaporation  from  the  stirred  soil  has  been  increased.  Here, 
again,  it  is  seen  that  rigid  physical  laws  and  conditions  have  set 
limitations  to  the  methods  of  tillage  as  a  substitute  for  irrigation. 

MIDSUMMER     AND    EARLY    FALL    CROPS    DIFFICULT    TO 
GROW    WITHOUT    IRRIGATION 

The  fact  that  after  early  summer  the  surface  of  the  ground 
usually  becomes  quite  dry,  coupled  with  the  other  fact  that  water 


130  Irrigation   and    Drainage 

percolates  and  travels  downward  through  such  soil  with  difficulty, 
makes  the  growing  of  a  second  crop  of  almost  any  kind  very 
difficult  and  uncertain  by  methods  of  tillage  unaided  by  irriga- 
tion. Every  one  is  familiar  with  the  fact  of  short  pastures  in 
midsummer  and  early  fall,  and  that  second  crops  of  hay  can  be 
raised  only  in  exceptional  seasons,  and  even  then  they  are  seldom 
heavy. 

The  difficulty  in  these  cases  is  not  that  less  rain  falls  during 
the  summer  and  autumn,  for  the  measured  amount  is  actually 
greater.  Neither  is  it  true  that  they  will  not  grow  because  it  is 
out  of  season,  for  when  plenty  of  water  is  supplied  heavy  crops 
of  grass  are  obtained  for  the  second  cutting.  As  a  matter  of 
fact,  the  summer  rains  are  less  effective  because  they  are  re- 
tained so  near  to  the  surface  as  not  to  come  within  reach  of  the 
roots  before  they  are  lost  by  surface  evaporation. 

In  our  own  experiments  in  irrigating  clover,  there  has  been 
secured  for  the  second  crop  of  clover  hay  1.789  tons  in  1895, 
2.035  tons  in  1896,  and  1.648  tons  of  hay,  containing  15  per  cent 
of  water,  in  1897,  or  an  average  for  three  years  of  1.824  tons  per 
acre.  When  it  is  recalled  that  the  average  yield  of  hay  per  acre 
for  the  thirteen  states  cited  is  but  little  more  than  1  ton  per  acre 
for  the  first  crop,  when  the  rains  have  their  maximum  effective- 
ness, it  is  plain  that  without  irrigation  it  is  not  possible  to  grow 
a  paying  second  crop  of  hay  to  any  extent  in  either  the  sub- 
humid  or  humid  parts  of  the  United  States.  Further  than  this, 
on  account  of  the  small  effectiveness  of  summer  rains,  it  is  often 
quite  impossible  to  secure  a  catch  of  clover  with  any  of  the  small 
grains,  while  with  irrigation  the  catch  would  be  positively  as- 
sured every  year.  These  are  cases  in  which  present  methods  of 
tillage  can  do  nothing,  but  in  which  irrigation  will  give  certain 
results. 

The  present  season  we  put  into  the  silo  6,552  pounds  of 
clover  and  volunteer  barley,  cut  from  .58  acres  of  ground  upon 
which  had  been  harvested  45  bushels  of  barley  to  the  acre.  This 
was  rendered  possible  by  irrigating  the  land,  and  thus  forcing 
the  new  seeding  of  clover  after  the  crop  was  removed.  In  this 
way  it  was  possible  to  get  two  good  crops  in  one  season  from  the 


Fall   Plowing   to    Conserve    Moisture  131 

same  piece  of  ground  ;  namely,  45  bushels  of  barley  per  acre, 
and  the  equivalent  of  1.4  tons  of  hay  containing  15  per  cent  of 
water.  Only  very  extraordinary  seasons  would  by  any  method 
of  tillage  permit  this  to  be  done. 


MEANS    OF    CONSERVING    MOISTURE 

1.    Fall  Plowing  to  Conserve  Moisture 

In  those  parts  of  the  world  where  winter  precipita- 
tion is  not  large,  so  as  to  over-saturate  the  soil,  and 
so  as  to  cause  the  running  together  of  soils,  and  thus 
destroy  their  tilth,  fall  plowing  may  be  found  very 
desirable  when  its  chief  object  is  to  diminish  surface 
evaporation  during  the  winter  and  early  spring,  and 
where  it  is  desirable  to  facilitate  the  ready  and  deeper 
penetration  of  the  water  into  the  soil  which,  during 
the  growing  season,  has  become  dried  to  considerable 
depths. 

In  order  that  fall  plowing  may  be  most  effective  in 
this  way,  it  should  be  done  as  late  as  practicable,  so 
that  its  looseness  may  not  be  destroyed  by  the  early 
rains,  and  its  usefulness  as  a  mulch  thus  reduced;  and 
also  in  order  that  it  may  allow  the  later  rains  and  melt- 
ing snows  to  drop  easily  and  more  completely  through 
it,  when  surface  drainage  will  be  prevented,  and  loss 
by  evaporation  will  be  reduced  to  the  minimum.  In 
such  conditions  capillarity  and  gravity  may  together 
aid  in  conveying  the  water  into  the  second,  third  and 
fourth  feet,  where  it  will  become  most  effective  in 
supplementing  the  spring  and  early  summer  rains. 

The  writer  has  shown,  in  "The  Soil,"  p.  187,  that 


132  Irrigation    and    Drainage 

land  in  Wisconsin  fall -plowed  late  in  the  season  was 
found  in  the  spring,  even  as  late  as  May  14,  to  con- 
tain not  less  than  6  pounds  of  water  to  the  square 
foot  more  than  similar  adjacent  land  not  so  treated. 
This  is  equivalent  to  1.15  inches  of  rain,  a  very 
important  quantity  to  have  been  stored  in  the  soil  at 
so  late  a  period  and  in  such  a  position  that  inter- 
tillage  is  certain  to  retain  it  for  service  when  it  is 
needed. 

It  will  be  readily  appreciated  that  this  sort  of  tillage 
to  conserve  moisture  is  most  .important  in  the  sub- 
humid  and  humid  climates,  whenever  those  dry  seasons 
occur  which  close  the  year  with  an  under -supply  of 
soil  moisture. 

It  should  not  be  inferred  that  this  sort  of  tillage  to 
save  moisture  must  be  confined  to  such  lands  as  are  to 
be  sowed  to  small  grains  in  the  spring,  or  even  planted 
to  corn  or  potatoes.  It  is  particularly  desirable  in  all 
lines  of  orcharding,  and  where  small  fruits  and  grapes 
are  grown.  The  laying  down  and  covering  of  the 
plants  need  not  prevent  it,  for  the  plowing  may  imme- 
diately precede  the  laying  down.  In  the  growing  of 
small  fruits  without  irrigation,  the  late  fall  tillage,  just 
before  the  ground  freezes,  is  a  matter  of  considerable 
moment,  because  with  strawberries,  raspberries  and 
blackberries  it  very  often  happens  that  a  shortage  of 
soil  moisture  just  at  the  fruiting  season  results  in  a 
very  serious  loss  through  a  reduction  of  the  yield, 
and  late,  deep  tillage  will  usually  lessen  this  danger. 
If  it  should  be  urged  by  some  that  this  practice 
applied  to  orchards  would  tend  to  stimulate  a  too  late 


Subsoiling    to    Conserve   Moisture 


133 


growth  of  wood  in  the  fall,  and  thus  lead  to  danger 
from  winter -killing,  the  reply  is  that  when  it  is  done 
late,  just  before  freezing  up,  there  can  be  no  danger 
on  this  score. 


2.  Subsoiling  to  Conserve  Moisture 

Subsoiling  to  conserve  soil  moisture  cannot  have 
the  extended  practice  that  methods  of  surface  tillage 
should,  but  there  are  cases  when  it  is  quite  likely  to 
prove  sufficiently  helpful  to  pay  for  the  relatively  heavy 
expense  which  it  involves.  In  view  of  this  fact,  and 
because  it  is  being  urged  particularly  in  the  sub-humid 


Fig.  24.    Method  of  determining  the  influence  of  subsoiling. 

belt,  the  principles  underlying  the  practice  should  be 
clearly  understood. 

The  method  used   to  demonstrate   the  influence  of 
subsoiling  in  retaining  the  rains  which  fall  upon  the 


134  Irrigation    and    Drainage 

ground  is  illustrated  in  Fig.  24,  where  all  losses  by 
surface  evaporation  were  prevented  by  placing  an  air- 
tight cover  over  the  areas  under  experiment.  In  order 
that  the  extreme  influence  of  subsoiling  might  be 
ascertained,  8  inches  of  the  surface  soil  was  completely 
removed  from  an  area  6x6  feet  on  a  side,  and  when 
the  subsoil  had  been  spaded  to  a  depth  of  13  inches 
more  it  was  returned  to  its  place  without  firming  in  any 
way,  except  to  smooth  the  surface  with  a  plank  pressed 
down  by  the  weight  of  a  man.  After  samples  of  soil 
had  been  taken  from  this  and  the  adjacent  area,  to  give 
the  existing  water  content,  water  was  slowly  sprinkled 
over  the  two  surfaces  until  254.41  pounds,  or  1.36 
inches,  had  been  added  to  each,  and  then  they  were 
covered,  as  shown  in  the  figure,  and  allowed  to  stand 
from  June  11  until  June  15,  when  the  covers  were 
removed  and  samples  of  soil  again  taken,  to  demon- 
strate what  changes  had  occurred. 

When  this  was  done  it  was  found  that  the  water 
added  had  effected  the  changes  which  are  recorded  in 
the  table  which  follows  : 

Subsoiled  Not  subsoiled         Difference 

LBS.  LBS.  LBS. 

The  first  foot  gained     124.6  102.1  4-22.5 

The  second  foot  gained 72.57  10.34  +62.23 

The  third  foot  gained 38.22  12.05  +26.17 

The  fourth  foot  gained     ...  33.26  3.82  +29.43 

The  fifth  foot  lost  . 2.29  19.5  —17.21 


Total  water  gained   268.65  128.31 

Total  water  added    . . .  254.41  254.41 


Difference +14.24          —1264 


Subsoiling   to    Conserve   Moisture  135 

It  will  thus  be  seen  that  the  subsoiled  ground, 
under  conditions  where  no  evaporation  could  take  place 
from  the  surface,  had  not  only  retained  all  the  water 
which  had  been  added  to  it,  but  that  it  had  actually 
gained  by  capillarity  from  the  adjacent  soil  14.24 
pounds  additional.  The  ground  not  subsoiled,  on  the 
other  hand,  had  actually  lost,  without  evaporation  from 
the  surface  of  the  soil,  126.1  pounds  of  water. 

In  a  second  experiment,  which  was  handled  in  the 
same  way,  except  that  no  water  was  added  to  the  sur- 
face, the  treated  soil  was  allowed  to  stand  from  June 
26  to  July  2,  covered  so  that  no  evaporation  could 
take  place  from  the  surface,  the  object  being  to  learn 
whether  capillary  action  would  draw  moisture  from 
below  into  the  subsoiled  earth,  and  thus  increase  its 
water  supply.  The  changes  which  took  place  are 
shown  by  the  following  figures  : 

ON  SUBSOILED  GROUND 
1st  foot       2nd  foot       3rd  foot       4th  foot       5th  foot 

PER  CENT  PER  CENT  PER  CENT  PER  CENT  PER  CENT 


July  2 

Change    .....         -  .63       +  .61        -  .36       +  .31      +  .72 

ON  GROUND  NOT  SUBSOILED 

June  26—  start  .  .  .         22.52         20.67        17.74        15.06       19.34 
July  2—  close  .....         23.97         22.09        18.92        14.62       18.38 


Change    +1.45       +1.32       +1.18      —.44     —.96 

It   appears  from   these  results  that   there  was  but 


136  Irrigation   and    Drainage 

little  tendency  for  the  deeper  soil  water  to  pass  upward 
by  capillarity  into  the  subsoiled  earth.  But  quite  the 
opposite  was  the  case  with  the  ground  not  subsoiled, 
for  here  the  upper  3  feet  had  each  gained  more  than 
1  per  cent  of  their  dry  weight  of  water.  Express- 
ing the  movement  which  had  taken  place  during  the 
6  days  in  pounds  of  water  on  the  36  square  feet  of 
surface,  we  find  that  the  surface  3  feet  had  gained 
129.69  pounds,  while  the  lower  2  feet  had  lost  53.52 
pounds,  leaving  an  absolute  gain  of  76.17  pounds.  In 
the  case  of  the  subsoiled  ground,  the  surface  3  feet 
showed  a  loss  of  11.14  pounds,  and  the  lower  2  feet  a 
gain  of  39.38,  making  an  absolute  gain  to  the  area  of 
only  28.24  pounds. 

In  another  field  trial,  when  a  piece  of  land  was 
subsoiled  on  October  22,  while  a  strip  on  each  side  of 
this  was  plowed  without  subsoiling,  the  water  in  the 
soil  was  found  in  the  spring  to  be  distributed  in  the 
manner  indicated  below : 

Subsoiled         Not  subsoiled 
in  the  field  in  the  field  Difference 

LBS.  LBS.  LBS. 

First  foot 15.47  17.41  —1 .94 

Second  foot 17.61  16.31  +1.30 

Third  foot.. 18.19  17.84  +.35 

Fourth  foot 17.83  17.20  +  .63 


Total 69.10  68.76  +.  34 

Here  it  will  be  seen  that  the  surface  foot  of 
subsoiled  ground  contained  nearly  2  pounds  less 
water  than  that  not  subsoiled,  but  that  the  absolute 


Subsoiling    to    Conserve    Moisture  137 

amount   of   water   in  the    two  cases  is   practically  the 
same. 

In  a  fourth  experiment  to  show  the  effect  of  sub- 
soiling  in  the  spring  on  the  water  content  of  the  soil 
in  the  fall,  one  of  the  small  areas  already  described  was 
allowed  to  stand  exposed  from  June  until  September, 
75  days,  without  in  any  way  disturbing  the  surface, 
except  to  keep  it  free  from  weeds  by  shaving  them  off 
with  a  sharp  hoe.  The  results  were  these  : 

Subsoilcd        Not  subsoiled 
ground  ground  Difference 

PER  CENT      PER  CENT      PER  CENT 

Firstfoot  17.07  18.91  —1.84 

Second  foot 23.29  19.42  +3.87 

Third  foot 22.76  17.78  +4.98 

Fourth  foot    16.35  14.19  +2.16 

Fifth  foot 18.14  19.20  —1.06 

Here,  again,  the  results  have  the  same  general  char- 
acter as  they  did  when  the  subsoil  period  was  from 
October  to  April,  the  surface  foot  of  subsoiled  ground 
being  the  dryest,  while  the  next  3  feet  are  more  moist. 
When  the  effect  of  subsoiling  in  this  case  is  expressed 
in  inches  of  rain,  the  gain  in  the  saving  of  soil  moisture 
amounts  to  1.64  inches,  which  is  a  very  important 
amount. 

The  effects  of  subsoiling  probably  do  not  last  much 
longer  than  a  single  season,  unless  there  has  been  but 
little  rain,  so  that  the  ground  has  never  been  thoroughly 
saturated,  permitting  it  to  again  settle  together.  In 
the  case  of  the  field  trial  here  reported,  samples  of  soil 
were  taken  on  the  same  ground  April  8,  April  16,  and 


138  Irrigation   and    Drainage 

again  May  5,  in  order  to  discover  whether  in  that  time 
progressive  changes  would  take  place.  Between  the 
first  and  last  date  there  had  been  a  total  rainfall  of  5.33 
inches,  making  conditions  very  favorable  indeed  to 
obliterate  the  effects  of  the  subsoiling  in  a  short  time. 
The  changes  which  these  rains,  together  with  the  fitting 
and  planting  of  the  ground,  produced,  are  shown  in  the 
table  below: 

. April  8 — April  16 

Not  Not 

Subsoiled    subsoiled    Difference    Subsoiled    subsoiled  Difference 

PER  CENT  PER  CENT  PER  CENT  PER  CENT  PER  CENT  PER  CENT 

First  ft 19.58  22.04  —2.46  20.80  22.88  —2.08 

Second  ft  .  19.01  17.61  +1.40  18.62  18.97  -  .3f> 

Third  ft...  17.39  17.06  +.33  16.48  16.70  -.22 

Fourth  ft..  16.79  16.20  +.59  16.11  16.50  -.39 

Not 
Subsoiled    subsoiled    Difference 

PER  CENT  PER  CENT  P£R  CENT 

Firstfoot  21.28  21.34  —.06 

Second  foot    .  .    19.02  19.11  —.09 

Third  foot 19.11  18.37  +.74 

Fourth  foot 16.67  17  —.33 

It  will  be  seen  that  the  difference  between  the  water 
in  the  soil  under  the  two  treatments  becomes  less  each 
time  the  samples  are  taken,  and  that  on  May  5  the  dif- 
ference between  them  had  nearly  disappeared.  But  it 
should  be  observed  that  this  close  agreement  at  the  last 
time  may  be  more  apparent  than  real,  on  account  of  the 
fact  that  a  rain  of  1.3  inches  had  fallen  on  May  1,  and 
it  is  possible  that  time  enough  had  not  yet  elapsed  to 
allow  an  equilibrium  to  be  established. 


Effects   of  Subsoiling  139 


EXPLANATION    OF     THE    MOISTURE    EFFECTS    OF 
SUBSOILING 

The  results  stated  show  that  subsoiling  produces  several  very 
distinct  effects,  so  far  as  soil  moisture  is  concerned,  and  these 
may  be  stated  as  follows  : 

1.  Subsoiling  increases  the  percentage   capacity  for  water  of 
the  soil  stirred. 

2.  Subsoiling  decreases  the  capillary  conducting  power  of  the 
soil  stirred. 

3.  Subsoiling   increases  the  rate  of   percolation  through  the 
soil  stirred,  or  its  gravitational  conducting  capacity. 

In  order  to  understand  how  these  effects  are  produced  by  sub- 
soiling,  it  is  necessary  to  have  clearly  in  mind  the  nature  of  the 
physical  changes  in  the  soil  which  the  operation  in  question  sets 
up.  In  the  small  plot  experiments  which  have  been  cited,  the 
subsoiling  had  the  effect  of  increasing  the  pore  space  in  the  soil 
stirred  at  the  rate  of  over  245  cubic  inches  per  cubic  foot,  or  14.2 
per  cent.  Further  than  this,  the  pore  space  so  added  consisted  in 
a  large  measure  of  cavities  which  were  so  large  that  air  and  water 
would  move  through  them  in  obedience  to  the  laws  which  govern 
the  flow  of  water  through  large  pipes,  rather  than  those  control- 
ling the  flow  through  capillary  tubes. 

It  must  here  be  born  in  mind  that  the  increase  of  space  was 
made  as  large  as  it  could  well  be,  and  hence  that  the  results  have 
a  maximum  value. 

How  subsoiling  increases  the  water  capacity  of  the  soil  stirred. — 
When  a  soil  is  broken  into  lumps  which  lie  loosely  together,  and 
these  lumps  are  saturated  with  water,  the  many  lumps  behave 
toward  that  water  much  as  if  each  were  a  short  column  of  soil 
which  is  in  contact  with  standing  water.  The  surface  film  of 
water  which  spans  the  pores  at  the  surface  of  the  saturated  lump 
of  soil  has  a  definite  strength,  and,  if  the  lump  is  not  too  large, 
can  hold  every  cavity  within  that  lump  completely  full  of  water, 
just  as  the  lump  of  sugar  dipped  into  the  tea  and  then  withdrawn 
comes  forth  completely  filled  with  the  fluid.  But  when  the  soil 


140  Irrigation   and    Drainage 

is  compact,  so  that  each  portion  is  part  of  one  long  and  continuous 
mass  extending  downward  several  feet  before  water  is  reached, 
the  surface  tension  of  the  water  is  not  strong  enough  to  maintain 
the  soil  cavities  full  of  water,  and  a  part  drains  away  downward. 

It  is  easy  to  demonstrate  the  nature  of  this  action  with  a  bit  of 
candle  wicking  2  or  3  feet  long,  or  with  two  or  three  folds  of  cot- 
ton wrapping  twine  loosely  twisted  together.  Placing  this  in  a 
basin  of  water  and  letting  it  become  saturated,  if  it  is  then  raised 
out  by  both  ends,  holding  it  nearly  horizontal  and  straight,  the 
water  very  soon  ceases  to  drip  from  it  ;  but  if  it  is  allowed  to  sag 
in  the  middle,  the  water  will  begin  to  drip  rapidly,  and  will  con- 
tinue to  do  so  until  a  new  equilibrium  has  been  reached.  The 
string  will  lose  its  water  still  more  rapidly  and  completely  if  it  is 
simply  suspended  from  one  end,  when  it  then  represents  the  long- 
est column  of  soil. 

How  subsoiling  decreases  the  capillary  conducting  power  of 
soils.— When  large  open  spaces  have  been  developed  in  a  soil  by 
any  means,  then  every  such  cavity  cuts  off  a  part  of  the  capil- 
lary passageways  through  which  the  water  might  travel  by  capillary 
conduction,  thus  making  the  amount  of  water  which  may  move  in 
a  given  direction  proportionally  smaller.  This  being  true,  when 
rain  falls  upon  subsoiled  ground  it  travels  downward  very  slowly 
through  it  until  after  the  soil  has  become  completely  filled,  and 
drainage  or  percolation  takes  place.  If,  then,  the  shower  is  not 
heavy  enough  to.  completely  fill  this  subsoiled  layer,  it  is  nearly 
all  retained  within  it  ;  whereas,  when  the  capillary  connection  is 
good,  then  so  soon  as  the  surface  layer  becomes  wetter  than  that 
below,  the  water  begins  to  move  under  the  impulse  of  capillaritv, 
and  will  continue  to  do  so  until  a  balance  has  been  reached. 

On  the  other  hand,  when  the  surface  of  the  subsoiled  ground 
has  become  dryer  through  evaporation  or  by  root  action,  water 
from  below  will  not  enter  it  as  rapidly  as  it  will  soil  not  so  treated. 
It  is  thus  capable  of  acting  as  a  deep  mulch,  to  diminish  the  loss 
of  water  by  capillary  movement  upward.  But  should  conditions 
chance  to  be  such  that  the  whole  root  system  of  the  crop  has  been 
developed  within  this  subsoiled  layer,  then  a  rapidly- growing  crop 
upon  it  might  suffer  for  want  of  water  when  there  was  an  abun- 


Effects   of  Subsoiling  141 

dance  of  it  in  the  unstirred  soil  below,  but  now  prevented  from 
rising  into  the  root  zone  by  the  reduced  rate  at  which  it  is  possible 
for  the  water  to  rise. 

This  is  a  matter  of  great  importance  to  comprehend,  because 
in  a  humid  climate,  where  the  subsoils  frequently  become  satu- 
rated with  water,  rendering  them  unfit  for  the  feeding  ground  of 
roots,  to  develop  a  deep  mulch  over  this  by  subsoiling  would  tend 
to  maintain  this  lower  soil  permanently  in  a  condition  which 
excludes  the  roots  of  plants  from  it,  while  at  the  same  time  that 
water  cannot  rise  into  the  loosened  soil  above,  and  a  drought 
actually  occurs  when,  if  the  field  had  not  been  subsoiled,  a  good 
supply  of  water  might  easily  be  reached  by  the  crop. 

In  the  arid  and  sub -humid  regions,  the  saturated  subsoil  is 
rarely  found,  except  for  short  periods,  at  long  intervals  apart, 
and  hence  there  is  little  danger  from  this  score  in  subsoiling  in 
these  climates. 

How  subsoiling  allows  the  water  to  enter  the  soil  more  readily. — 
From  what  has  already  been  said,  it  wiJl  be  understood  that  it  is 
only  after  the  subsoiled  layer  has  become  saturated  that  water 
begins  to  percolate  through  it,  and  so  to  store  itself  in  the 
undisturbed  layer  below.  But  when  rain  enough  has  fallen  to 
accomplish  this  result,  then  whatever  else  falls  drops  readily  and 
rapidly  through  it,  not  only  because  there  are  wider  channels  for 
the  water  to  move  through  under  the  stress  of  gravity,  but  because 
from  an  open  soil  the  air  escapes  quickly  and  readily,  thus  making 
place  for  the  water  which  cannot  enter  until  the  space  for  it  has 
been  vacated.  The  water  entering  the  soil  in  time  of  rain  or  irri- 
gation is  like  water  entering  an  open-mouthed  jug,  which  can  only 
do  so  as  rapidly  as  the  air  is  permitted  to  escape. 

A  larger  percentage  of  the  water  contained  by  subsoiled  ground 
available  to  crops. — With  all  soils,  of  whatever  kind,  there  is  a  cer- 
tain amount  of  water  they  contain  which  it  is  impossible  for  the 
roots  of  plants  to  remove  with  sufficient  rapidity  to  meet  their 
needs,  and  this  amount  is  relatively  smaller  in  the  coarse-grained 
soils  than  it  is  in  those  having  a  finer  texture.  But  whenever  any 
soil  has  been  subsoiled,  and  its  water-holding  power  thereby 
increased,  this  extra  amount  of  water  becomes  wholly  available  to 


142  Irrigation   and    Drainage 

the  plant ;  and  if  this  amount  would  have  been  lost,  either  by 
downward  percolation  or  by  evaporation  from  the  surface,  then  the 
subsoiling  has  been  a  gain. 

3.    Earth  Mulches 

When  the  damp  surface  of  a  soil  is  covered  with  a 
dry  layer  of  earth,  the  rate  of  evaporation  from  it  is 
very  much  decreased.  It  is  because  of  this  fact  that 
thorough  surface  tillage  is  able  to  so  conserve  the  soil 
moisture  stored  in  the  upper  four  to  six  feet  of  culti- 
vated fields  that  fair  crops  may  be  grown  with  very 
little  rain ;  and  it  is  in  the  effective  handling  of  these 
mulches  that  the  hope  of  farmers  in  sub -humid  districts 
must  be  laid. 

Conditions  modifying  the  effectiveness  of  mulches. —  The  laws 
which  govern  the  loss  of  water  through  mulches  have  not  yet 
been  sufficiently  worked  out  to  permit  a  full  discussion  of  this 
important  subject,  but  several  important  facts  have  been  defi- 
nitely settled,  and  may  be  here  stated. 

In  the  first  place,  when  other  conditions  are  the  same,  the 
thicker  or  deeper  the  layer  of  loose,  dry  soil  is,  the  less  rapidly 
can  the  soil  moisture  pass  upward  through  it,  to  be  lost  by 
evaporation. 

It  was  found,  for  example,  that  when  soil  covered  with  no 
mulch  lost  water  in  the  still  air  of  the  laboratory  at  the  rate  of 
4.375  acre-inches  per  100  days,  the  same  soil  stirred  to  a  depth 
of  .5  inches  lost  but  4.017  acre-inches,  and  when  stirred  to  a 
depth  of  .75  inches  lost  3.169  acre -inches  in  the  same  time.  In 
another  case,  when  the  loss  of  water  from  the  unmulched  surface 
was  6.2  acre -inches  per  100  days,  stirring  this  same  soil  to  a 
depth  of  1  inch  reduced  the  loss  to  4  acre -inches,  while  stirring 
it  to  a  depth  of  2  inches  left  the  loss  but  2.8  acre-inches  per 
100  days. 

So,  too,  when  corn  was  cultivated   to  a   depth  of   1  to  1.5 


Mulches    to    Conserve    Moisture  143 

inches  with  a  Tower  cultivator,  and  adjacent  rows  were  culti- 
vated to  a  depth  of  3  inches  with  narrow  shovels,  it  was  found  at 
the  end  of  the  season  that  the  ground  cultivated  3  inches  deep 
contained  1.478  inches  more  water  than  the  1-inch  cultivation 
did  in  the  upper  4  feet,  the  conditions  of  the  soil  being  as  repre- 
sented below  : 

1st  foot       2nd  foot       3rd  foot         4th  foot 

PER  CENT      PER  CENT       PER  CENT        PER  CENT 

Cultivated  3  inches  deep 23.14  23.3  21.94  22.46 

Cultivated  1  inch  deep 22.7  21.08  19.65  19.58 

Difference .44  2.22  2.29  2.88 

These  differences  do  not  show  the  amount  of  water  which  the 
deeper  mulch  saved,  because  at  several  times  during  the  season 
the  rains  may  have  brought  the  soil  of  the  two  kinds  of  treat- 
ment very  close  together  in  their  water  content,  the  results  above 
being  simply  the  final  difference.  They  do  show,  however,  how 
much  more  moist  one  soil  was  kept  than  the  other,  and,  hence, 
how  much  better  were  the  conditions  in  one  case  than  in  the 
other  for  plant  growth. 

That  the  full  significance  of  such  differences  in  soil  moisture 
in  crop  production  may  be  better  appreciated,  Fig.  25  shows  the 
growth  of  corn  under  every  way  similar  conditions,  except  that 
the  amounts  of  water  in  the  soil  in  which  the  corn  was  large 
and  in  which  it  was  small  were  as  stated  in  the  table  which 
follows : 

Moisture  in  soil  Moisture  in  soil 

of  largest  corn  of  smallest  corn 

PER  CENT  PER  CENT                Difference 

First  foot 13.29  10.18  3.11 

Second  foot 17.23  16.33  .9 

Third  foot 19.17  18.63  1.08 

Fourth  foot 16.21  1548  .73 

These  differences,  it  will  be  noted,  are  much  smaller  than  in 
the  case  cited  above.  But  let  it  be  observed  that  the  difference  in 
the  surface  foot  here  is  very  much  larger  than  there,  and  it  is  the 
shortage  of  water  in  this  layer  which  is  chiefly  responsible  for  the 
difference  in  growth  shown  in  the  figure. 


144  Irrigation   and    Drainage 

The  character  of  the  mulch,  also,  has  an  important  influence 
on  the  amount  of  water  which  is  permitted  to  escape  through  it. 
Thus,  it  was  found  that  when  the  same  soil  was  covered  to  a  depth 


Fig.  25.    Difference  in  growth  of  corn  where  there  is  a  difference  of 
3  per  cent  of  soil  moisture  in  the  siirface  foot. 

of  2  inches  with  mulches  of  different  kinds,  the  observed  loss  of 
water  per  100  days  was  as  stated  below : 

INCHES 

Through  2-inch  mulch  of  coarse  sand l.l 

"  "       "  black  marsh  soils 3.9 

'  fine  clay  loam 3.9 

"  dry  peat 2 

"  clay  loam,  crumb-form 2.8 

From  these  results  it  is  seen  that  a  coarse-grained  texture 
produces  a  better  mulch  than  one  extremely  fine  ;  that  is,  the  loss 
of  water  by  evaporation  through  the  coarsest  sand  was  less  rapid 
than  it  was  through  the  fine  sand,  and  it  was  more  rapid  through 
the  finely  powdered  clay  loam  than  it  was  through  the  same  soil 
left  in  the  crumbled  condition  in  which  we  usually  find  it  when 
the  soil  is  in  good  tilth.  The  small  loss  from  the  peat  mulch,  too, 
was  due  largely  to  the  fact  that  it  did  not  rub  down  to  a  fine 
texture. 

Just  why  this  law  holds  for  soil  mulches  cannot  now  be  stated, 
except  that  it  seems  evident  that  the  water  is  not  lost  by  direct 
evaporation  at  the  surface  of  the  damp  soil,  for  in  that  case  we 
should  expect  the  largest  losses  to  take  place  from  the  mulches 
having  the  most  open  structure,  and  the  least  when  the  diameter 


Mulches   to    Conserve   Moisture  145 

of  the  pore  spaces  is  smallest,  but  which  observation  proves  not 
to  be  true.  The  only  explanation  which  now  occurs  to  the  writer 
for  the  law  is,  that  even  in  the  air -dry  condition  of  soil,  the  film 
of  moisture  still  investing  the  soil  grains,  although  so  extremely 
thin,  is  subject  to  the  same  disturbance  by  evaporation  at  the 
exposed  surface  that  it  is  when  that  film  is  much  thicker,  as  in  the 
case  of  soils  containing  the  right  amount  of  moisture  for  plant 
growth,  and  when  evaporation  from  the  surface  takes  place 
rapidly. 

Earth  mulches  lose  in  effectiveness  with  age. — When  a  good 
earth  mulch  has  been  developed,  it  does  not  remain  equally  effec- 
tive for  an  indefinite  period,  even  if  no  rain  falls  upon  it.  This  is 
particularly  true  early  in  the  season,  when  the  amount  of  soil 
moisture  is  high,  and  when  it  tends  to  creep  into  the  lower  part 
of  the  mulch,  saturating  it  and  causing  the  open  texture  to 
disappear  by  breaking  down  the  crumb  structure,  and  thus  restor- 
ing the  original  and  normal  capillary  power.  A  soil  mulch  devel- 
oped to  a  depth  of  two  or  three  inches  thus  grows  gradually 
thinner  with  age  by  reverting  to  the  original  condition.  This  be- 
ing true,  it  is  necessary,  when  the  greatest  protection  is  desired, 
to  repeat  the  stirring  of  the  soil  as  often  as  observation  shows  that 
its  effectiveness  has  been  impaired. 

Mulches  that  are  not  made  from  soil. —  By  far  the  largest  part 
of  the  protection  offered  against  the  loss  of  water  by  surface 
evaporation  from  the  soil  is  and  must  be  furnished  by  mulches 
developed  from  the  soil  itself.  But  it  should  be  understood  that 
all  vegetation  growing  upon  the  surface  of  a  field,  whether  it 
completely  covers  the  ground  or  not,  exerts  a  protective  influence, 
tending  to  diminish  the  loss  of  water  from  the  surface  of  the 
ground.  This  protection  comes  partly  from  shading  the  ground, 
partly  from  a  reduction  of  the  wind  velocity  close  to  the  surface, 
and  partly  from  the  tendency  of  vegetation,  by  the  transpiration 
from  its  foliage,  to  saturate  the  air  with  moisture,  and  so  reduce 
the  rate  of  evaporation  which  otherwise  would  be  possible. 

Even  in  pastures  where  the  grass  is  short,  if  it  is  only  close 
and  completely  covers  the  ground  with  its  foliage,  the  mulching 
influence  is  marked.  Hence,  in  order  to  get  the  largest  returns 


146  Irrigation   and    Drainage 

from  the  natural  rainfall  on  pasture  land,  great  care  should  be 
taken  to  keep  it  in  such  condition  that  the  whole  surface  is  well 
and  closely  covered  with  vegetation.  Of  course,  the  same  remarks 
apply  to  meadow  lands. 

Too  close  pasturing  is  very  wasteful  in  every  way.  The 
animals  themselves  are  not  fed  properly,  the  grass  is  not  permitted 
to  have  foliage  enough  for  the  most  vigorous  growth,  and  so  much 
of  the  surface  of  the  ground  is  exposed  to  the  sun  that  evapora- 
tion directly  from  the  soil  is  rapid  and  a  dead  loss,  not  only  doing 
no  good  in  itself,  but  throwing  out  of  use  the  upper  layer  of  soil, 
in  which  the  nitrifying  processes  should  be  permitted  to  go  for- 
ward rapidly,  because  it  is  too  dry  for  them. 

The  surface  dressing  of  meadows  with  a  good  coating  of 
farmyard  manure,  and  then  harrowing  this  thoroughly  to  spread  it 
evenly  over  the  surface,  is  extremely  beneficial,  not  simply  because 
of  the  plant- food  which  it  contains,  but  because  of  the  mulching 
effect  which  it  furnishes  to  shade  the  naked  spots  of  soil  and 
those  which  are  only  thinly  covered.  When  this  dressing  is 
applied  very  early,  and  is  early  spread  over  the  surface,  while 
the  soil  is  yet  damp,  it,  of  course,  does  the  most  good,  both  as  a 
mulch  and  as  a  plant -food  ;  for  then  fermentation  goes  on  better 
in  the  manure,  and  the  moisture  dissolves  out  the  soluble  parts 
and  conveys  it  to  the  roots  of  the  grass.  Then,  too,  in  the  case 
of  thin  meadows,  if  new  grass  and  clover  seed  are  added  at  the 
same  time,  before  the  harrowing,  much  of  it  will  be  sufficiently 
covered  by  the  harrowing  and  shaded  by  the  manure  to  allow  it  to 
germinate,  and  thus  thicken  up  the  meadow  and  bring  it  back  to 
its  proper  condition. 

Harrowing  and  rolling  small  grain  after  it  is  up. —  When  the 
ground  is  closely  covered  with  plants,  as  in  the  case  of  oats, 
wheat  and  barley  sowed  broadcast  or  in  close  drills,  advantage 
has  sometimes  been  found  in  either  harrowing  the  ground  or  in 
rolling  it  for  the  express  purpose  of  changing  the  character  of  the 
surface.  The  changes  thus  wrought  have  sometimes  a  double 
effectiveness,  in  that  a  thin  mulch  is  produced  which  in  a  meas- 
ure reduces  the  direct  loss  of  water  through  the  surface  soil  by 
evaporation  from  it  ;  and  in  breaking  up  a  crust  which  forms 


Early    Tillage    to    Conserve   Moisture  147 

over  plowed  fields  when  a  considerable  evaporation  has  taken 
place  from  the  wet  surface,  and  which,  on  account  of  the  shrink- 
age and  of  the  salts  brought  to  the  surface  by  the  soil  water,  tend 
to  close  up  the  soil  pores,  and  thus  interfere  with  the  proper 
entrance  of  air  to  it,  which  is  essential  to  the  best  results.  Roll- 
ing in  such  cases  will  seldom  do  much  good,  except  where  the 
ground  was  left  somewhat  uneven  at  the  time  of  seeding,  either 
by  the  drill  ridges  or  by  those  left  by  the  harrow,  or  unless  there 
are  many  small  lumps,  which  the  rolling  tends  to  break  down, 
forming  from  them  and  the  ridges,  or  both,  a  thin  mulch.  The 
harrowing  in  such  cases  has  a  wider  range  than  rolling,  and  is 
often  likely  to  be  more  effective.  But  neither  of  these  treat- 
ments should  be  given  except  when  the  soil  of  the  field  is  dry 
and  crumbly  at  the  surface,  for  otherwise  no  mulch  will  be  formed, 
and  the  effect  would  be  to  increase  rather  than  diminish  the  loss 
of  water  from  the  soil  by  surface  evaporation  from  it. 

4.    Early  Tillage  to  Conserve  Moisture 

It  has  already  been  pointed  out  that  tillage  to 
conserve  moisture  is  most  useful  in  humid  climates 
when  it  is  applied  as  early  in  the  season  as  the  condi- 
tion of  the  soil  will  admit.  But  the  case  is  stated  in 
the  most  general  terms  when  it  is  said  that  tillage, 
to  save  moisture,  should  be  given  to  the  soil  just  as 
soon  after  the  wetting  of  the  surface  as  it  is  possi- 
ble to  do  so  without  puddling  or  otherwise  injuring 
its  texture. 

Let  it  be  fully  understood  that  tillage  to  save  soil 
moisture  is  concerned  almost  wholly  with  the  saving 
of  that  which  has  penetrated  the  soil  to  a  depth  exceed- 
ing that  of  the  mulch  developed  by  stirring,  As  a 
thoroughly  effective  soil  mulch  cannot  be  readily  made 
having  a  depth  less  than  2  to  3  inches,  it  follows  that 


148  Irrigation    and    Drainage 

tillage  to  conserve  soil  moisture  is  chiefly  concerned 
with  saving  moisture  which  has  penetrated  the  ground 
to  a  depth  exceeding  2.5  to  3  or  more  inches.  The 
moisture  which  is  caught  and  held  by  the  soil  closer 
to  the  surface  than  stated  must  usually  be  taken  up 
directly  by  the  surface  feeding  roots,  or  it  must  be 
lost  by  surface  evaporation. 

When  .the  snows  and  frosts  of  winter  have  melted, 
and  the  earliest  spring  rains  have  come,  the  soil  is 
usually  left  so  moist  as  to  be  fully  saturated  with 
water  to  a  depth  exceeding  1,  2,  and  even  3  feet, 
according  as  the  snows  or  rains  have  been  copious  or 
light.  At  the  same  time,  the  texture  of  the  surface 
soil  has  been  so  changed  as  to  place  it  in  the  very 
best  possible  condition  for  rapidly  conveying  the  deeper 
soil-water  to  the  surface,  where,  if  the  sun  shines  and 
a  brisk,  dry  wind  is  blowing,  it  will  be  lost  with  great 
rapidity,  sometimes  in  single  exceptionally  favorable 
days  amounting  to  2,  3,  and  even  4  pounds  per  square 
foot  per  day,  equivalent  to  more  than  40,  60  and  80 
tons  per  acre. 

But  these  high  rates  of  loss  are  not  maintained, 
fortunately,  for  long  periods  of  time,  even  when  there 
has  been  no  effort  made  to  prevent  them.  We  have, 
however,  measured  losses  during  seven  days  amounting 
to  9.13  pounds  per  square  foot,  or  at  a  daily  rate  of 
1.3  pounds;  and  in  four  days  a  rate  as  high  as  1.77 
pounds  per  square  foot.  Under  extremely  favorable 
conditions,  and  where  the  surface  of  the  soil  was  kept 
continuously  wet,  we  have  measured  a  mean  daily  loss 
by  evaporation  as  great  as  2.37  pounds  for  fine  sand, 


Early    Tillage   to    Conserve   Moisture  149 

and  2.05  pounds  for  a  clay  loam,  per  day  and  per 
square  foot. 

As  soon  as  the  surface  of  the  soil  becomes  air -dry, 
the  rate  of  evaporation  from  it  is  very  much  slower, 
for  in  this  condition  it  does  not  conduct  the  water 
upward  as  rapidly  as  when  nearly  saturated.  Early 
tillage  contributes  to  this  end,  and  thus  greatly  di- 
minishes the  losses  which  would  occur  early  in  the 
season. 

There  is  no  tool  made  which  produces  a  more 
effective  mulch  than  the  common  plow,  which  cuts  off 
completely  a  layer  of  soil  of  the  depth  desired  and 
lays  it  down  bottom  up  in  a  loose,  crumbled  condition, 
reducing  the  capillary  conducting  power  to  the  mini- 
mum. It  is  not  possible,  however,  to  use  the  plow  as 
early  in  the  season  as  some  of  the  other  tools,  like  the 
harrow ;  neither  is  it  possible  to  cover  the  ground  as 
rapidly  with  it.  Further  than  this,  it  is  often  unde- 
sirable to  stir  the  soil  as  deep  as  it  must  be  worked 
with  the  plow,  in  order  to  make  a  good  mulch ;  and 
so  one  or  another  form  of  harrow  is  used  instead. 

When  small  grains  are  sowed  on  fall  plowing,  or 
on  corn  or  potato  ground  without  plowing,  it  is 
important  to  start  the  surf  ace -working  tools  at  the 
very  earliest  possible  moment,  not  simply  to  save 
moisture  by  developing  a  mulch,  but  to  aerate  and 
warm  up  the  surface  soil,  so  that  the  nitrates  may 
begin  to  be  developed  and  placed  in  readiness  for  the 
crop  which  is  to  follow.  It  is  this  saving  of  moisture, 
and  the  early  and  abundant  development  of  soluble 
plant -food,  which  is  invariably  associated  with  and  the 


150  Irrigation   and    Drainage 

direct  result  of  a  thorough  preparation  of  the  seed- 
bed, which  has  always  led  the  most  successful  farmers 
to  insist  upon  the  importance  of  a  good  seed-bed. 

Let  it  be  remembered  that  it  is  the  early  stirring 
of  the  soil,  rather  than  the  early  planting  of  the  seed, 
which  is  the  all -important  point  to  be  insisted  upon. 
Nothing  is  gained  by  putting  seed  in  a  soil  which  is 
too  cold  ;  but  several  days  may  often  be  saved  in  bring- 
ing the  soil  to  the  right  temperature  by  stirring  a  suf- 
ficient depth  of  it  for  the  seed-bed,  and  getting  rid 
of  the  surplus  water  which  it  contains  by  cutting  it 
loose  from  the  wet  soil  below,  and  at  the  same  time 
concentrating  the  heat  from  the  sun  in  this  stirred 
layer,  because  loosening  it  has  made  it  a  poor  con- 
ductor to  the  unstirred  cold  soil  below  it. 

Even  when  ground  is  not  to  be  planted  until  quite 
late,  as  in  the  case  of  corn  and  potatoes,  it  is  a  far 
better  practice  to  plow  as  early  as  other  labor  will  per- 
mit, than  to  leave  it  unstirred  until  near  the  planting 
time,  because  the  early  fitting  develops  plant -food  and 
gets  it  in  readiness  for  the  crop ;  because  it  saves 
moisture  ;  because  it  prevents  clods  from  forming,  and 
insures  a  more  perfect  tilth,  and  because  it  allows  one 
and  sometimes  two  crops  of  weeds  to  be  killed  before 
the  planting.  This  last  advantage  is  a  very  important 
one,  because  weeds  can  be  killed  much  more  cheaply 
and  effectively  when  there  is  nothing  on  the  ground 
in  the  way,  and  because  it  is  a  very  wasteful  practice 
to  permit  weeds  to  start  in  a  field,  to  use  up  both  the 
moisture  and  the  plant -food  which  will  be  needed  by 
the  crop.  It  is  much  better  to  plant  late,  and  take 


Plowing    Under    Green   Manures  151 

time  enough  to  have  everything  in  the  best  possible 
condition,  than  to  rush  the  seed  in  early  and  expect 
to  do  the  fitting  and  weed -killing  afterward. 

The  importance  of  observing  the  practice  here 
pointed  out  increases  more  and  more  as  we  pass  from 
the  more  humid  climates  to  the  semi -humid  ones. 
Be  it  remembered  that  it  is  important  not  simply  from 
the  soil  -  moisture  side,  but  from  the  plant -food  side  as 
well ;  for  plant -food  cannot  be  developed  in  the  soil 
without  the  right  conditions  of  moisture,  temperature 
and  air,  all  of  which  are  secured  by  early,  thorough  and 
frequent  tillage  before  the  seed  is  in  the  ground. 


5.    The  Danger  of  Plowing  Under  Green  Manures 

In  both  humid  and  sub-humid  climates,  where  irri- 
gation is  not  practiced,  the  use  of  green  crops  for  ma- 
nures in  the  spring  cannot  be  looked  upon  as  always 
a  rational  practice,  unless  it  be  on  grounds  which  are 
naturally  sub -irrigated,  or  for  other  reasons  are  natu- 
rally too  wet.  The  difficulties  standing  in  the  way  of 
this  practice  are  these :  If  the  green  manure  crop 
should  be  rye,  or  anything  of  that  character,  its  ten- 
dency to  remove  from  the  soil  all  of  the  nitrates  and 
other  soluble  plant -foods  as  rapidly  as  they  can  be 
formed  leaves  the  soil  for  the  time  being  impover- 
ished ;  and  it  can  be  readily  understood  that  if  another 
crop  like  corn  or  potatoes  is  put  at  once  upon  the 
ground,  in  weather  when  germination  takes  place 
quickly,  this  crop  would  find  itself  placed  under  con- 
ditions in  which  it  will  be  forced  to  wait,  or  at  best  to 


152  Irrigation   and    Drainage 

grow  slowly,  until  time  enough  shall  have  elapsed  for 
the  processes  of  fermentation  to  be  set  up  in  the  green 
crop  which  shall  reconvert  it  into  available  plant- 
food.  But  if  the  spring  should  chance  to  be  a  dry 
one,  so  that  the  crop  of  green  manure  has  itself  left 
the  soil  deficient  in  moisture,  or  if  the  capacity  of  the 
soil  for  moisture  is  naturally  small,  then  there  will  be 
present  in  the  soil  neither  moisture  enough  to  make 
the  green  crop  turned  under  ferment  rapidly,  nor  to 
enable  the  planted  crop  to  make  the  best  growth,  even 
where  there  is  an  abundance  of  plant -food  in  the 
soil. 

The  sowing  of  a  catch  crop  in  the  fall  in  humid 
climates  is  not  open  to  the  same  objection,  for  then 
this  crop  has  a  tendency  to  gather  up  available  ni- 
trates which  develop  during  the  warm  part  of  the  fall, 
after  the  crop  has  been  taken  off  the  ground,  and  to 
carry  them  through  the  winter  in  an  insoluble  form, 
so  that  they  are  not  lost  by  drainage.  But  to  bring 
them  into  requisition,  especially  if  the  season  or  soil 
is  at  all  dry,  it  is  important  that  this  should  be  turned 
under  early,  and  a  sufficient  interval  of  time  allowed 
to  intervene  for  fermentation  to  take  place  before  the 
seed  of  the  new  crop  is  put  upon  the  ground. 

In  sub -humid  climates,  on  soils  that  are  not  sub- 
ject to  washing,  it  is  very  doubtful  if  there  is  any 
advantage  to  be  gained  from  catch  crops,  as  such, 
even  when  sown  in  the  fall ;  for  in  those  cases  there  is 
neither  winter  nor  spring  leaching  of  the  soil,  and  as 
there  is  naturally  a  deficiency  of  soil  moisture,  the  indi- 
cations are  that  very  early  fall  plowing,  to  develop  a 


Summer   Fallowing   and   Soil   Moisture         153 

new  mulch  to  lessen  further  evaporation  during  the 
fall  and  winter,  and  to  permit  nitrification  in  the  fall  to 
be  carried  forward,  is  likely  to  leave  the  soil  in  a  much 
better  condition  for  the  next  season,  both  as  to  moisture 
and  available  nitrates,  than  could  be  hoped  for  by  the 
other  method. 

It  is  not  only  difficult  to  get  a  good  catch  crop  in  the 
fall  on  account  of  deficient  moisture,  but  there  is  during 
the  growing  season  of  the  sub -humid  climate  so  little 
moisture  that  a  rapid  rate  of  nitrification  in  the  soil 
is  impossible,  and  hence  all  the  time  which  can  be  had 
for  this  purpose  is  needed  in  order  to  have  enough 
nitrates  developed  for  the  crop  the  next  year. 

6.    Summer  Fallowing  in  Relation  to  Soil  Moisture 

The  old  practice  of  summer  fallowing,  which  it  has 
been  the  fashion  for  writers  on  agricultural  chemistry 
to  discourage  of  late  years,  has  really  much  more  of 
merit  in  it,  as  indeed  practical  experience  has  proved, 
than  has  been  recently  taught.  It  is  not  here  intended 
to  convey  the  idea  that  there  are  not  soils  and  climates 
in  which,  in  the  majority  of  seasons,  it  would  be  better 
not  to  summer  fallow,  on  account  of  there  being  danger 
of  an  excessive  development  of  nitrates,  which  would  be 
lost  by  drainage  ;  but  there  is  much  to  suggest  that  in 
rich  soils  which  are  usually  deficient  in  soil  moisture, 
as  in  many  sub -humid  sections,  there  is  not  mois- 
ture enough  in  a  single  year  to  develop  the  requisite 
amount  of  plant -food  and  to  mature  the  crop  as  well, 
and  hence,  that  some  form  of  summer  fallowing,  or 


154  Irrigation   and    Drainage 

practice  which  is  equivalent  to  it  in  effect,  will  be  found 
to  give  better  results  than  steady  cropping,  either  with 
or  without  catch  crops. 


INFLUENCE  OF  SUMMER  FALLOWING  ON  SOIL  MOIS- 
TURE AND  ON  PLANT -FOOD 

In  a  study  on  the  influence  of  summer  fallowing  on  the  water 
content  of  the  soil,  it  was  found  that  the  effect  still  showed,  even 
at  the  end  of  the  following  season,  after  a  crop  had  been  matured 
on  the  ground.  In  order  to  show  how  great  this  influence  may 
be,  the  results  of  the  study  are  cited  here,  giving  first  the  con- 
dition of  the  soil  in  the  spring,  when  the  fallowing  experiment 
was  begun.  The  results  cited  are  from  three  adjacent  plots,  the 
middle  plot  being  the  one  bearing  the  crop.  The  table  which 
follows  shows  the  water  content  of  the  plots  as  given  by  three 
determinations,  on  May  22,  June  11,  and  June  17,  the  averages 
being  given  in  every  case,  and  the  data  from  the  two  fallow 
plots  being  combined: 


0-12  inches 

Ground  to  be 
left  fallow 

PER  CENT 
23  63 

Ground  not  to  be 
left  fallow 

PER  CENT 

21  49 

12-18 

19  78 

18  57 

24-30 

18  06 

18  13 

36-42       "       

15  50 

17  48 

48-52       " 

19.03 

18.91 

Mean 19.20  18.92 

Here  it  will  be  seen  that  there  is  a  slight  tendency  for  the 
ground  left  fallow  to  be  a  little  wetter  than  that  which  was  to 
bear  the  crop,  but  this  difference  is  not  as  large  as  the  table 
shows,  because  the  fallowing  effect  had  begun  to  show  its  in- 
fluence somewhat  when  the  last  two  sets  of  samples  were  taken, 
corn  having  already  begun  to  grow  upon  the  intervening  plot. 

At  the  end  of  the  growing  season,  August  24,  the  difference 


Summer   Fallowing   and   Soil   Moisture  155 

in  the  water  content  of  the  soil  under  the  two  treatments  was 
found  to  be  as  given  in  the  table  below  : 

Not  fallow  ground  rear  bv 

Fallow  ground    Not  fallow  ground    Timothy  and  Clover 

No  crop                     Corn                    bluegrass  in.  pasture 

PER  CENT        PER  CENT         PER  CENT  PER  CENT 

0-6  inches 16.23                           6.97                           6.55  8.39 

6-12      "       17.74                            7.8                              7.62  8.48 

12-18      '        19.88                           11.6                            11.49  12.42 

18-24      "       19.84                          11.98                           13.58  13.27 

24-30      "       18.56                          10.84                          13-26  13.52 

40-43      "                             15.9                              4.17                          18.51  9.53 


In  the  first  half  of  this  table,  where  the  soils  are  closely 
similar  and  entirely  comparable  in  every  way,  it  will  be  seen 
that  the  ground  bearing  no  crop  is  much  more  moist  than  is 
that  on  which  the  corn  was  grown ;  and  since  a  good  degree  of 
moisture  in  the  surface  foot  of  soil  is  absolutely  indispensable 
to  the  processes  which  develop  the  available  nitrates,  it  can  readily 
be  seen  how  much  more  favorable  were  the  conditions  for  the  for- 
mation of  nitrates  on  the  fallow  ground  than  they  were  on  the 
ground  which  was  not  fallow.  In  the  last  two  columns  of  the 
table,  there  has  been  set  down,  for  the  sake  of  comparison,  the 
results  of  moisture  determinations  at  corresponding  depths  on 
lands  bearing  pastured  clover  in  one  case  and  hay  in  the  other. 
These  samples  were  taken  from  essentially  the  same  kinds  of  soil, 
and  but  a  short  distance  from  where  the  other  samples  were 
taken,  and  illustrate  in  a  very  forcible  manner  how  thoroughly 
the  surface  foot  of  soil  in  a  dry  time  loses  its  moisture  when  it 
is  occupied  by  a  crop,  and  how  unfavorable  are  the  conditions 
for  nitrification  in  the  soil  when  compared  with  those  offered  by 
the  fallow  ground. 

In  the  following  spring,  after  the  frost  was  out  of  the  ground, 
and  the  fall  and  winter  rains  and  snows  had  given  their  moisture 
to  the  plots  under  experiment,  samples  of  soil  were  again  taken, 
to  learn  what  the  relative  conditions  were  at  this  time,  and  the 
results  found  are  given  in  the  table  below,  where  both  the  per- 


156 


Irrigation    and    Drainage 


centage  of  water  in  the  soil  and  the  number  of  pounds  of  water 
per  cubic  foot  are  given  : 

Table  showing  the  water  content  in  the  spring,  in  soil  ichich  the  year  before  had 
been  fallow  and  not  falloiv 


Depth 
of  sample 

Fallow 

PER  CENT 

Not 
fallow 
PER  CENT 

Difference 

PER  CENT 

Fallow 
LBS. 

Not 
fallow 

LBS. 

Difference 

LBS. 

First  foot  

19.43 

16.61 

2.82 

15.01 

12.83 

2.18 

Second  foot.. 

20.55 

17.76 

2.79 

16.4 

14.17 

2.23 

Third  foot..., 

18.56 

16.09 

-'.47 

17.47 

15.15 

2.32 

Fourth  foot  .  .  , 

17.78 

15.11 

2.67 

17.44 

14.82 

2.62 

Sum  . . 


66.32         56.97 


9.35 


This  table  shows  that  the  fallow  ground  starts  out  in  the 
spring  with  9.35  pounds  of  water  to  the  square  foot  more  than 
the  ground  not  fallow  did  in  its  upper  four  feet,  besides  having 
a  much  higher  percentage  of  available  nitrogen  in  the  soil.  How 
much  greater  the  available  nitrogen  was  is  not  known,  except 
that  in  another  trial,  ground  which  had  been  fallow  the  year 
before  produced  practically  the  same  yield  as  did  a  strip  which 
received  a  good  dressing  of  farmyard  manure. 

At  the  end  of  harvest  the  same  year,  samples  of  soil  were 
again  taken  on  the  ground  which  had  been  fallow  and  on  that 
which  had  not  been  fallow,  the  results  standing  as  shown  below: 


Table  showing  the  water  content  of  soil  at  the  end  of  harvest,  which  the 
preceding  year  had  been  fallow,  and  had  not  been  fallow 

• Ground  with  oats « Ground  with  barley > 

Not  Not 

Callow      fallow      Difference 

LBS.  LBS.  LBS. 

9.06  7.08  1.98 

11.90  10.10  1.80 

12.48  10.60  1.88 

14.07  11.52  2.55 


Depth 

Fallow 

fallow 

Differen 

of  sample 

LBS. 

LBS. 

LBS. 

First  foot  

6.01 

3.74 

2.27 

Second  foot  

9.65 

4.45 

5.20 

Third  foot  

9.54 

9.30 

.24 

Fourth  foot  

8.93 

8.43 

.50 

Sum. 


34.13 


25.92 


8.21 


47.51 


39.30 


8.21 


The  data  of  this  table  show  very  clearly  that  summer  fallow- 
ing exerts  a  marked   influence  upon  the  relation  of  the  soil  to 


Old   System    of  Intertillage  157 

water,  and  one  which  is  great  enough  to  modify  the  water  con- 
tent of  the  soil  throughout  the  whole  of  the  following  season  under 
crop.  The  table  shows  that  where  oats  were  grown,  the  soil, 
when  the  crop  had  been  harvested,  contained  8.21  pounds  of 
water  per  square  foot,  or  1.57  inches  more  than  did  the  ground 
which  had  not  been  summer  fallowed  the  year  before.  The  same 
difference  also  existed  on  the  barley  ground,  and  in  both  cases 
notwithstanding  the  fact  that  larger  yields  of  both  straw  and 
grain  had  been  produced  on  the  fallow  ground, 


7.    The  Old  System  of  Intertillage 

The  old  system  of  horse- hoe mg,  introduced  by 
Jethro  lull  in  England,  and  modified  by  Hunter,  and 
still  later  by  Smith,  at  Lois-Weedon,  has  much  to  rec- 
ommend it  on  fertile  soils,  in  which  there  is  a  deficiency 
of  soil  moisture,  as  is  the  case  in  the  sub -humid 
regions  of  this  country.  Tull  was  a  close  observer, 
and  early  learned  to  appreciate  the  great  advantage 
of  thorough  tillage,  not  only  in  conserving  soil  mois- 
ture, but  also  in  developing  available  plant-food.  He 
strongly  advocated  planting  in  drills,  so  as  to  admit 
of  thorough  and  frequent  stirring  of  the  soil  and  with 
the  aid  of  the  horse. 

Hunter  modified  lull's  system  by  laying  out  his 
fields  in  strips  about  9  feet  wide,  every  other  one  of 
which  was  sown,  while  the  intermediate  ones  were 
left  naked,  and  were  frequently  cultivated  through  the 
season,  and  kept  free  from  weeds.  In  the  fall  of  the 
year  the  bare  strips  were  sown,  and  the  others,  which 
had  borne  the  crop,  were  plowed  up  and  tilled  in  a 
similar  manner.  His  method  amounted  to  a  system 


158  Irrigation    and    Drainage 

of  summer  .fallowing,  as  that  practice  is  now  generally 
understood,  except  that  it  possessed  one  important  ad- 
vantage :  namely,  his  strips  being  so  narrow,  and  hence 
so  numerous,  that  both  the  moisture  saved  by  the  til- 
lage and  the  nitrates  developed  became  available  to 
the  plants  growing  along  the  margin.  Further  than 
this,  a  part  of  the  rain  which  fell  upon  the  strips, 
both  by  its  lateral  capillary  movement  and  by  the 
development  of  roots  into  this  unoccupied  ground, 
contributed  to  the  growth  of  the  crop  as  though  it 
had  been  partially  irrigated,  or  its  rainfall  had  been 
increased,  which  in  fact  it  had. 

The  Rev.  Mr.  Smith,  at  Lois-Weedon,  in  North- 
amptonshire, raised  wheat  very  successfully  by  still  a 
different  modification  of  TulPs  idea.  His  practice 
was  to  sow  about  one  peck  of  seed  to  the  acre,  by 
dropping  the  grains  3  inches  apart  in  three  rows  1  foot 
apart,  and  leaving  a  space  3  feet  wide  unplanted  be- 
tween each  group  of  three  rows.  These  strips  were 
thoroughly  tilled  until  the  wheat  was  in  bloom,  and 
kept  free  from  weeds.  He  even  went  to  the  extent  of 
trenching  the  naked  strip,  bringing  up  some  of  the 
subsoil  and  putting  the  surface  loam  into  the  trenches. 
By  his  thorough  tillage,  thorough  aeration  and  con- 
servation of  soil  moisture,  he  was  able  to  maintain  a 
yield  of  18  to  20  bushels  per  acre  without  manure. 

These  cases  of  old  and  now  generally  abandoned 
practice  are  called  up  here  because  they  involve  a 
principle  which,  when  correctly  applied,  is  of  great 
importance  in  sub -humid  climates,  where  water  for 
irrigation  is  not  available.  The  principle  referred  to 


Old    System   of  Intertillage  159 

is  that  of  using  the  rain  which  falls  upon  an  acre  of 
ground  to  produce  a  crop  on  one -half  of  that  same 
area.  For  this,  as  a  matter  of  fact,  was  the  essential 
thing  which  the  Lois-Weedon  system  did.  It  is  evi- 
dent enough  that  in  a  country  where  the  rain  which 
falls  is  only  one -half  the  amount  which  is  needed  to 
produce  remunerative  crops,  if  that  water  can  be 
brought  to  use  on  one -half  of  the  area,  then  a  fair- 
crop  on  one -half  of  the  ground  may  reasonably  be 
expected. 

The  important  matter,  then,  is  to  devise  a  system 
of  planting  for  the  various  crops  which  shall  permit 
the  rain  which  falls  upon  the  unused  area  to  be 
brought  within  reach  of  the  plants  growing  upon  the 
occupied  ground.  For  all  crops  which  are  grown  in 
hills  or  in  rows,  like  maize,  potatoes,  and  various 
vegetables,  the  problem  is  simple  enough,  as  it  resolves 
itself  into  the  single  question  of  how  many  plants  can 
be  matured  upon  the  ground  with  the  available  water, 
allowing  for  unavoidable  losses.  This  fixes  the  dis- 
tance between  the  rows  and  the  distance  between  the 
hills  in  the  row.  In  countries  where  there  is  an 
abundance  of  water,  or  where  irrigation  is  practiced, 
plants  may  be  brought  so  close  together  that  the  limit- 
ing factor  is  amount  of  sunshine,  or  available  plant- 
food  in  the  soil,  or  air  about  the  plant ;  but  in  sub- 
humid  regions,  the  limiting  factor  is  water  alone,  and 
the  distance  between  plants  must  be  made  such,  if 
necessary,  that  the  roots  of  one  will  not  encroach  upon 
the  feeding  ground  of  another. 

The   roots    of    the   maize    plant    commonly    spread 


160  Irrigation    and    Drainage 

laterally  to  a  distance  of  3.5  to  4.5  feet ;  hence,  if 
necessary,  the  rows  of  corn  might  be  placed  as  far  as 
7  to  8  feet  apart,  and  yet  be  able  to  take  moisture 
from  the  whole  field.  Taking  the  extreme  case  of 
rows  8  feet  apart  and  plants  2  feet  apart  in  the  row, 
the  number  of  plants  per  acre  would  be  2,725.  Sup- 
posing each  plant  to  produce  a  large  stalk  and  large 
ear,  the  total  weight  of  dry  matter  for  the  acre  might 
be  2,157.5  pounds,  giving  18.32  bushels  of  shelled 
corn.  This  yield  of  dry  matter  per  acre  would  call 
for  only  2.577  acre -inches  of  water  to  produce  it,  at 
the  rate  of  the  results  which  have  been  obtained  from 
52  trials  in  Wisconsin. 

Potato  roots  spread  laterally  to  the  distance  of  2 
to  2.5  feet ;  hence  these  might  be  planted  in  rows  4 
to  5  feet  apart  without '  having  the  roots  overlap  in 
the  feeding  ground.  The  chief  advantage  of  wider 
rows  for  potatoes  in  the  sub -humid  climate  comes  in 
its  permitting  intertillage  after  the  vines  have  reached 
full  size,  and  thus  better  conserving  the  scanty  mois- 
ture, so  important  in  the  later  development  of  the 
tubers,  and  which  would  travel  laterally  by  capillarity 
toward  the  roots  in  case  they  did  not  reach  the  center. 
The  table  which  follows  shows  the  actual  distribution 
of  soil  moisture  in  the  upper  18  inches  of  a  potato 
field  in  which  the  rows  extended  east  and  west,  and 
were  planted  3  feet  apart,  under  flat  cultivation : 


Old    System    of  Intertillage  161 

Table  showing  the  distribution  of  moisture  in  a  potato  patch,  June  27 


Midway 
between  rows 

Nine  inches 
south  of  row 

In  the  row 

Nine  inches 
north  of  row 

Depth  of  sample 

PER  CENT 

PER  CENT 

PEtt  CENT 

PEE  CENT 

0-6    inches 

23.50 

18.37 

17.80 

23 

6-12       " 

19.03 

18.13 

17.40 

18.50 

12-18       " 

20.73 

21.43 

19.53 

21.40 

0-18  20.99  19.31  18.24  20.97 

At  the  time  these  determinations  were  made,  the 
potato  vines  were  about  one -half  full  size.  It  will  be 
seen  that  the  moisture  had  been  withdrawn  from  the 
soil  more  completely  at  18  inches  directly  below  the 
center  of  the  hill  than  it  had  at  18  inches  on  either 
side.  It  does  not  follow  from  this,  however,  that  the 
plants  were  not  receiving  important  additions  of  soil 
moisture  from  the  soil  in  the  center  of  the  row.  In 
our  work  in  irrigating  potatoes,  where  the  rows  were 
30  inches  apart,  and  where  ridge  culture  was  adopted, 
the  water  being  applied  in  furrows  about  9  inches 
wide,  it  was  found  that  on  the  boundary  between  the 
irrigated  and  non- irrigated  areas,  the  second  row  of 
potatoes  from  the  last  water  furrow  had  its  yield 
increased  on  the  average,  in  1897,  7.9  bushels  per 
acre,  or  3.2  per  cent  of  the  yield  of  merchantable 
tubers  grown  on  the  land  not  irrigated.  That  is  to 
say,  the  lateral  capillary  movement  of  the  water  in 
irrigation  influenced  the  yield  to  that  extent  through 
a  distance  of  about  40  inches. 

In  the  case  of  corn,  the  second  rows  beyond  the 
last  irrigating  furrow  showed  the  influence  of  the 
water  to  the  extent  of  2.2  per  cent  of  the  non- 


162  Irrigation    and    Drainage 

irrigated  yield,  and   through  a    distance  of    about  58 
inches. 

Then,  again,  in  the  case  of  some  experimental  plots 
of  oats  which  were  separated  by  a  naked  strip  2  feet 
wide,  and  kept  free  from  weeds  by  surface  hoeing,  the 
following  distribution  of  water  was  found  on  July 
19,  1889: 

Table  showing  distribution  of  soil   moisture  in  oats  and  in  adjacent 
fallow  strip  2  feet  wide 

In  oats  2  ft.    In  oats  1  ft.       At  edge        In  center 

from  path      from  path          of  oats  of  path      Difference 

Depth  of  sample         PEK  CENT       PER  CENT       PER  CENT      PER  CENT    PER  CENT 

0-6   inches  8.08  11.43  3.35 

6-12     "  7.51  11.80  4.29 

12-18     "  10.61  15.42  4.81 

18-24      "  14.01  18.78  4.77 


0-24  10.40  10.05  10.70  14.35 

It  will  be  seen  from  these  percentages  that  there  is 
a  very  marked  higher  per  cent  of  water  in  the  fallow 
strip  than  there  is  immediately  adjacent  to  it  in  the 
oats,  and  from  this  it  might  be  inferred  that  the  oats 
was  not  being  fed  from  the  fallow  strip.  This  inference, 
however,  would  not  be  correct,  for  it  was  found  that 
the  yield  of  oats  on  a  strip  1  foot  wide,  on  the  south 
side  of  the  path,  was  39  per  cent  larger  than  from  a 
corresponding  area  in  the  center  of  the  plot  12  feet 
wide,  while  the  yield  on  the  north  side  of  the  path 
was  28.7  per  cent  larger,  showing  very  clearly  that 
there  was  better  feeding  in  consequence  of  the  narrow 
2-foot  path. 

In  view  of  such  facts  as  these,  and  practical  experi- 


Old   System   of  Intertillage  163 

ence,  it  is  not  unreasonable  to  expect  that  where  there 
is  a  deficiency  of  water  in  the  soil,  the  small  grains 
may  be  sown  in  narrow  strips  of  4  to  6  drill  rows, 
9  inches  apart,  separated  by  naked  strips  30  inches 
wide,  which  may  be  cultivated  to  yield  up  their  mois- 
ture and  developed  nitrates  to  the  growing  grain  on 
either  side,  and  thus  mature  heavier  crops  of  well- 
filled  grain  than  would  be  possible  if  the  seeds  were 
scattered  evenly  over  the  whole  surface,  none  of  which 
could  be  cultivated. 

Such  a  practice  as  is  here  suggested  is  manifestly 
summer  fallowing,  but  in  a  very  different  way,  and 
for  quite  a  distinct  purpose,  from  that  usually  had  in 
mind.  Of  course,  it  would  not  be  urged,  except  on 
soil  and  in  climates  in  which  there  is  an  insufficient  sup- 
ply of  soil  moisture  to  mature  the  crop  under  ordinary 
methods  of  handling.  The  method,  however,  has  a 
rational  basis  for  sub -humid  climates  and  for  the 
lighter  soils  of  small  water  capacity  in  the  more  humid 
climates;  but  it  cannot  be  hoped  that  it  will,  under 
these  conditions,  give  as  large  yields  per  acre  when 
figured  upon  the  whole  area  as  the  closer  planting  on 
the  soils  better  supplied  with  soil  moisture.  Neither 
can  it  be  expected  that  crops  can  be  raised  as  cheaply 
by  this  method  as  by  the  ordinary  methods.  All  that 
can  be  asserted,  or  can  be  reasonably  expected,  is  that 
better  crops  can  be  raised  by  it  in  sub -humid  climates 
and  on  the  lighter  soils  in  humid  climates,  than  can 
be  raised  by  the  ordinary  methods.  It  is  not  an  easy 
matter  to  adapt  the  method  either  to  growing  hay  or 
to  maintaining  pastures  of  the  ordinary  sort. 


164  Irrigation    and    Drainage 


8.    Frequency  of  Tillage  to  Conserve  Soil  Moisture 

Tillage  to  conserve  soil  moisture,  like  water  for  irrigation, 
cannot  be  applied  except  at  an  increased  cost  of  production. 
Hence,  to  cultivate  a  field  when  there  is  nothing  to  be  gained 
from  it  is  to  be  avoided.  In  the  early  part  of  the  growing  sea- 
son, when  the  soil  is  so  fully  charged  with  moisture  that  a  small 
rain  easily  causes  the  soil  granules  to  coalesce  and  destroy  the 
effectiveness  of  mulches,  it  is  often  desirable  to  repeat  the  culti- 
vation or  harrowing  as  often  as  there  has  been  a  shower  of  suffi- 
cient intensity  to  establish  good  capillary  connection  between 
the  stirred  and  unstirred  soil. 

It  is  often  of  the  greatest  importance  that  this  reestablish - 
ment  of  the  mulch  should  take  place  at  the  earliest  possible 
moment,  not  only  because  of  the  rapid  loss  of  water  from  wet 
surfaces,  but  because  of  the  fact  that,  when  the  surface  soil  has 
reached  a  certain  degree  of  dryness  while  the  deeper  soil  is  yet 
wet,  the  moisture  of  the  surface  layer  so  strengthens  the  upward 
movement  of  soil  moisture  into  that  layer  that  not  only  is  all 
of  the  rain  held  at  the  surface,  but  a  very  considerable  amount 
of  the  deeper  soil  water  is  brought  there  also.  Our  studies  have 
proved,  both  by  observation  and  by  repeated  experiment,  that 
wetting  the  surface  of  the  ground  may  leave  the  deeper  soil 
actually  dryer  than  it  was  before,  and  if  the  new  mulch  is  not 
early  developed  the  rain  may  leave  the  surface  four  feet  dryer 
than  it  would  have  been  had  the  rain  not  occurred. 

Then,  too,  in  the  early  part  of  the  year,  there  are  so  many 
advantages  to  be  gained  through  frequent  stirring  of  the  soil, 
other  than  the  saving  of  moisture,  that  the  slightest  reason  for 
going  over  the  ground  again  should  lead  to  its  being  done.  But 
as  the  season  advances,  and  the  soil  has  become  dryer  to  con- 
siderable depths,  then  the  desirability  of  frequent  stirrings  of 
the  surface  to  develop  or  restore  the  texture  of  the  mulch,  is 
much  less.  This  is  so,  partly  because  when  the  surface  of  the 
ground  is  dry,  it  is  an  excellent  mulch,  even  though  it  is  quite 
firm  and  close  in  texture  ;  but  also,  because  the  smaller  showers 


Ridged   or   Flat    Cultivation  165 

of  the  later  season  are  largely  retained  very  close  to  the  surface, 
so  that  stirring  the  surface  may  hasten  the  evaporation  of  it,  and 
at  the  same  time  prevent  a  part  of  it  from  being  conducted 
downward  into  the  soil  by  capillarity. 

Further  than  this,  in  the  latter  part  of  the  season  many  plants 
in  humid  climates  put  out  new  roots,  which  reach  up  extremely 
close  to  the  surface,  in  order  to  take  advantage  of  the  showers 
whose  waters  are  retained  there;  and  tillage  at  once  after  a 
rain  may  do  positive  injury  to  the  crop,  by  destroying  these  roots 
before  they  have  conveyed  the  soil  moisture  to  the  plant,  heavily 
laden  with  plant-food,  as  it  is  likely  to  be  under  these  conditions. 

9.    Proper  Depth  of  Surface  Tillage  and  Ridged  or 
Flat  Cultivation 

It  will  be  readily  inferred,  from  what  has  already  been 
said,  that  the  best  depth  of  tillage  will  vary  with  the  season. 
Early  in  the  season  it  should  almost  invariably  be  deep,  not  less 
than  2  to  3  inches,  but  rarely  should  it  be  deeper  than  this.  The 
deep  stirring  in  the  spring  is  to  develop  fertility  by  thoroughly 
aerating  the  soil  and  making  it  warm,  so  that  the  nitrates  are 
rapidly  formed.  Later  in  the  season  the  cultivation  should  be- 
come more  and  more  shallow,  until,  as  already  pointed  out,  it 
should  be  finally  abandoned  altogether. 

When  it  is  stated  that  the  early  tillage  should  have  a  depth  of 
2  to  3  inches,  this  should  be  understood  as  meaning  that  the 
whole  surface  of  ground  not  occupied  by  the  plants  should  be 
stirred  to  this  depth,  and  some  tool  which  actually  displaces  the 
whole  of  the  soil  to  a  uniform  depth  does  the  best  work.  As  a 
rule,  the  field  should  not  be  furrowed  with  deep  grooves  and 
ridges,  for  this  method  early  dries  out  too  large  a  volume  of  the 
soil,  and  thus  lessens  its  productive  power.  Indeed,  it  should 
always  be  kept  in  mind  that  the  surface  soil  in  humid  climates  is 
the  most  valuable  soil  of  the  field ;  and  for  this  reason,  after  the 
period  of  stirring  for  fertility  is  passed,  as  little  should  be  moved 
and  allowed  to  become  dry  as  will  answer  the  needs  of  the  mulch, 
because  in  this  condition  the  soil  is  valueless  in  plant  feeding. 


166  Irrigation   and    Drainage 

Throwing  a  field  into  ridges  with  deep  furrows  between,  as  is 
done  with  some  of  the  wide -shovel  cultivators,  and  as  used  to 
be  done  generally  in  laying  corn  by,  has  little  to  recommend  it 
except  on  flat  fields  of  stiff,  heavy  soil,  in  wet  climates  or  seasons. 
The  chief  objection  to  the  ridges  and  furrows  is  that  they  greatly 
increase  the  evaporating  surface  and  the  amount  of  soil  which  is 
thrown  out  of  use.  In  the  case  of  potatoes,  however,  especially 
on  the  heavy  soils,  the  last  cultivation  should  be  to  hill  them  in 
order  to  form  a  loose,  deep,  mellow  soil,  in  which  the  tubers  may 
form  and  expand  without  meeting  with  excessive  resistance. 
Indeed,  it  is  quite  doubtful  whether  there  are  many  soils  in  which 
potatoes  will  not  do  better  if  hilled  to  some  extent  the  last  thing 
before  the  vines  spread  to  cover  the  ground.  The  earlier 
cultivation  should  by  all  means  be  flat. 


10.    Rolling  in  Relation  to  Soil  Moisture 

The  roller  has  an  extensive  use  in  many  localities 
in  fitting  land  for  crops  in  the  spring  or  fall.  It 
should  be  understood,  however,  that  when  the  surface 
of  a  field  is  finished  with  a  heavy  roller,  it  is  left  in 
a  condition  in  which  its  moisture  will  be  rapidly  lost, 
and  for  several  reasons  : 

1.  Firming   the   surface  reestablishes  the   capillary 
connection  with   the    soil   below,  and   the    moisture    is 
brought  to  the  surface  quickly  from  depths    as    great 
as  four  feet.     The  appearance  to  the  eye  is  that  the 
ground  is  made  more  moist,  and  so  it  is  at  the  sur- 
face, as  a  matter  of   fact,  but  it  must  never  be  for- 
gotten that  this  is  at  the  expense  of  moisture  stored 
deep  in  the  ground. 

2.  Rolling    leaves    the   surface   smooth    and   even, 
so   that   it   absorbs   heat   rapidly  from    the   sun   on   a 


Rolling   in   Relation    to    Soil   Moisture          167 

clear  day,  and  becomes  warmer  below  the  surface  than 
ground  not  rolled.  This  hastens  the  rate  of  evapo- 
ration from  the  surface.  Then,  too,  this  smooth  sur- 
face allows  the  wind  velocity  to  be  much  greater  close 
to  the  ground,  and  on  this  account  the  loss  of  water 
is  increased. 

It  is  often  desirable  to  use  the  heavy  roller  in  fit- 
ting ground  for  seed,  and  sometimes  for  the  express 
purpose  of  bringing  an  increased  amount  of  moisture 
to  the  seed,  in  order  to  hasten  or  to  ensure  germi- 
nation when  the  soil  has  become  dry.  But  when  this 
has  been  found  desirable,  the  roller  should  immedi- 
ately be  followed  with  a  light  harrow,  in  order  to 
restore  a  thin  mulch,  which  shall  check  the  loss  by 
evaporation  from  the  surface  without  at  the  same 
time  preventing  the  rise  of  water  from  below  to  mois- 
ten the  soil  about  the  seed. 

The  press -drill,  which  has  been  invented  to  assist 
germination,  and  avoid  some  of  the  bad  effects  of  the 
roller,  is  a  tool  employing  a  sound  principle.  The 
seed  is  well  covered  to  begin  with,  and  then  the  soil 
directly  above  it  is  firmed  by  the  press -wheel,  while 
the  intervening  soil  is  left  loose,  to  act  as  a  mulch 
and  diminish  the  loss  of  water,  which  would  be  inevi- 
table with  the  roller.  This  tool,  however,  has  a  much 
safer  application  in  the  sub -humid  regions  than  it 
has  in  the  East,  where  the  soil  in  the  spring  is  natu- 
rally more  moist,  and  where,  for  this  reason,  there  is 
danger  of  the  seed  being  so  closely  covered  that  an 
insufficient  amount  of  air  gets  to  it  to  enable  it  to 
germinate  properly. 


168  Irrigation    and    Drainage 

11.    Lessening  Destructive  Effects  of  Winds 

In  sub  humid  climates,  especially  like  those  of  our 
western  prairies,  where  there  is  a  high  mean  wind 
velocity,  and  in  the  level  districts  of  humid  climates, 
where  the  soils  are  light  and  sandy,  with  a  small 
water  capacity,  and  which  are  lacking  in  adhesive 
quality,  the  fields  may  suffer  greatly  at  times,  not 
only  from  excessive  loss  of  moisture,  but  the  soil  itself 
may  be  greatly  damaged  by  drifting  caused  by  the 
winds.  Under  such  conditions,  it  is  a  matter  of  great 
importance  that  the  wind  velocities  close  to  the  sur- 
face should  be  reduced  as  much  as  possible. 

We  have,  in  Wisconsin,  extensive  areas  of  light 
lands  which  almost  every  year  suffer  severely  from 
the  drifting  action  of  the  winds.  On  these  lands, 
wherever  broad  open  fields  lie  unsheltered  by  any 
windbreak,  the  clearing  west  and  northwest  winds 
which  follow  storms  not  only  rapidly  dry  out  the  soil, 
but  often  sweep  entirely  away  crops  of  grain  after 
they  are  4  inches  high,  uncovering  the  roots  by  the 
removal  of  1  to  3  inches  of  the  surface  soil.  It  has 
been  observed,  however,  in  these  districts,  that  where- 
ever  there  are  windbreaks  of  any  sort,  even  such  slight 
barriers  as  fences  and  even  fields  of  grass,  a  marked 
protection  against  drifting  has  been  experienced  for 
several  hundred  feet  to  the  leeward  of  them. 

In  the  case  of  groves,  hedgerows,  and  fields  of 
grass,  the  protection  results  partly  from  their  ten- 
dency to  render  the  air  which  passes  across  them  more 
moist,  and  partly  by  lessening  the  surface  velocity  of 


Lessening   Destructive   Effects   of   Winds        169 

the  wind.  The  writer  has  observed  that  when  the 
rate  of  evaporation  at  20,  40,  and  60  feet  to  the  lee- 
ward of  a  grove  of  black  oak  15  to  20  feet  high  was 
11.5  c.c.,  11.6  c.c.,  and  11.9  c.c.,  respectively,  from  a 
wet  surface  of  27  square  inches,  it  was  14.5,  14.2  and 
14.7  c.c.,  at  280,  300  and  320  feet  distant,  or  24  per 
cent  greater  at  the  three  outer  stations  than  at  the 
nearer  ones.  So,  too,  a  scanty  hedge-row  produced 
observed  differences  in  the  rate  of  evaporation  as  fol- 
lows, during  an  interval  of  one  hour : 

At  20  feet  from  the  hedge -row  the  evaporation  was  10.3  c.c. 
At  150  "  "  "  "  "  "  "  12.5  c.c. 

At  300     "        "        "  "  "  "  "      13.4  c.c. 

Here  the  drying  effect  of  the  wind  at  300  feet  was 
30  per  cent  greater  than  at  20  feet,  and  7  per  cent 
greater  than  at  150  feet  from  the  hedge. 

Then,  too,  when  the  air  came  across  a  clover  field 
780  feet  wide  the  observed  rates  of  evaporation  were  : 

At    20  feet  from  clover 9.3  c.c. 

At  150     "        "          "      12.1  c.c. 

At  300     "        "          "       13     c.c. 

Or  40  per  cent  greater  at  300  feet  away  than  at  20  feet, 
and  7.4  per  cent  greater  than  at  150  feet. 

The  protective  influence  of  grass  lands,  and  the  dis- 
advantage of  very  broad  fields  on  these  light  lands, 
was  further  shown  by  the  increasingly  poorer  stand  of 
young  clover  as  the  eastern  margin  of  these  fields  was 
approached,  even  when  the  drifting  had  been  inappre- 
ciable. Below  are  given  the  number  of  clover  plants 


170  Irrigation    and    Drainage 

per  equal  areas  on  three  different  farms  as  the  distance 
to  the  eastward  of  the  grass  fields  increased  :  No.  1,  at 
50  feet,  574  plants;  at  200  feet,  390  plants;  at  400  feet, 
231  plants.  No.  2,  at  100  feet,  249  plants;  at  200  feet, 
277  plants  ;  at  400  feet,  193  plants  ;  at  600  feet,  189 
plants  ;  at  800  feet,  138  plants  ;  and  at  1,000  feet,  48 
plants.  No.  3,  at  50  feet,  1,130  plants;  at  400  feet,  600 
plants;  at  700  feet,  543  plants. 

In  these  cases  the  difference  in  stand  appears  to 
have  resulted  from  an  increasing  drying  action  of  the 
wind.  On  most  of  the  fields,  the  destructive  effects 
of  the  winds  were  very  evident  to  the  eye,  and  aug- 
mented as  the  distance  from  the  windbreaks  increased. 

It  appears  from  these  observations,  and  from  the 
protection  against  drifting  which  is  afforded  by  grass 
fields,  hedgerows,  and  groves,  that  a  system  of  rotation 
should  be  adopted,  on  such  lands,  which  avoids  broad, 
continuous  fields.  The  fields  should  be  laid  out  in  nar- 
row lands,  and  alternate  ones  kept  in  clover  or  grass. 
Windbreaks  of  suitable  trees  must  also  have  a  beneficial 
effect  upon  the  crops  when  maintained  along  fields,  rail- 
roads, and  wagon  roads  in  such  places  as  have  been 
described,  and  especially  in  the  prairie  sections  of  the 
sub -humid  regions,  where  irrigation  cannot  be  prac- 
ticed. It  is,  of  course,  true  that  trees  on  the  margins 
of  fields  sap  the  soil  in  their  immediate  vicinity,  and 
thus  reduce  the  yield  there  ;  but  it  seems  more  than 
probable  that  in  open,  windy  sections  their  protective 
influence,  which  it  has  been  shown  they  exert,  will 
much  more  than  compensate  for  this  where  there  is  a 
general  deficiency  of  soil  moisture. 


CHAPTER  IV 

THE   INCREASE   IN   YIELD    DUE    TO    IRRIGATION  IN 
HUMID    CLIMATES 

IN  order  to  know  how  important  the  right  amount 
of  soil  moisture,  applied  at  the  right  time,  is,  and  in 
order  to  know  whether  it  will  pay  to  irrigate  in  humid 
climates,  it  is  necessary  to  learn  what  yields  are  possi- 
ble under  the  best  conditions  when  the  crop  must 
depend  upon  the  natural  rainfall,  and,  side  by  side 
with  these  in  time  and  place,  to  measure  the  possible 
increase  in  yield  due  to  irrigation,  if  any  there  be. 

When  the  study  of  the  importance  of  soil  moisture, 
and  the  principles  underlying  the  methods  of  saving 
and  utilizing  it,  were  begun  at  the  Wisconsin  station 
in  1888,  it  very  early  became  evident  that,  in  order  to 
learn  just  how  important  it  is  in  plant  culture  to  con- 
serve the  soil  moisture,  some  method  must  be  adopted 
which  would  permit  of  giving  to  the  plants  under  inves- 
tigation all  the  water  they  can  use  to  advantage. 
This  led  to  the  series  of  experiments  which  have  been 
recorded  in  the  introductory  chapter,  aiming  to  meas- 
ure the  amount  of  water  which  different  cultivated 
plants  can  use  under  the  conditions  of  field  life.  But 
when  the  results  attained  under  the  methods  there  used 
showed  that  such  large  yields  are  possible,  it  became 

(171) 


172  Irrigation    and    Drainage 

important  to  supplement  the  rainfall  under  wholly 
normal  field  conditions,  to  see  if  there  would  then  be 
any  notable  increase  over  the  yields  produced  under 
the  natural  field  conditions.  This  led  to  a  series  of 
experiments  to  be  conducted  parallel  with  those  on  till- 
age, to  learn  how  far  short  of  possible  yields  our  actual 
ones  are  when  secured  under  the  best  moisture  relations 
at  our  command  ;  and  irrigation  experiments  as  checks 
on  our  tillage  experiments  were  begun,  the  results  of 
which  it  is  important  to  state. 

In  conducting  these  control  experiments  on  irriga- 
tion, the  aim  has  been  to  treat  the  crop  growing  under 
the  conditions  of  the  normal  rainfall  and  under  those 
of  the  rainfall  supplemented  \>y  irrigation,  exactly 
alike  in  every  way  until  it  became  apparent  that  more 
water  might  be  used  with  advantage,  when  water  was 
applied  to  the  control  plots  as  often  as  it  seemed  de- 
sirable. No  other  elements  of  difference  have  been 
introduced  than  those  growing  out  of  applying  the 
additional  water. 

IMPORTANCE     OP     THE     AMOUNT     AND     DISTRIBUTION     OF 

WATER    IN    POTATO    CULTURE,    AND    THE    ADVANTAGE 

OF    IRRIGATION    IN    CLIMATES    LIKE    WISCONSIN 

There  have  been  two  seasons'  work  with  this  crop,  1896  and 
1897,  and  both  years  the  potatoes  have  been  planted  in  rows  30 
inches  apart  and  in  hills  15  inches  in  the  row,  or  else  twice  that 
distance.  The  ground  in  each  case  was  given  a  good  dressing  of 
farmyard  manure,  plowed  in  6  inches  deep.  Large  tubers  were 
used  for  seed,  cut  two  eyes  to  the  piece,  and  planted  with  hoe 
about  3  inches  deep,  and  the  ground  harrowed  after  planting. 


Increase    of  Potato    Crop    by    Irrigation         173 

The  Rural  New-Yorker  has  been  the  chief  variety  grown,  but 
each  year  an  unnamed  variety  of  the  Burbank  type  has  been  used 
to  finish  out  the  piece. 

The  potatoes  were  planted  about  the  middle  of  May  each  year, 


Fig.  26.    Difference  in  yield  between  Rural  New-Yorker  potatoes, 
irrigated  and  not  irrigated,  in  1896. 


Fig.  27. 


Difference  in  yield  between  potatoes  of  Burbank  type  irrigated 
and  not  irrigated,  in  1896. 


Fig.  28.    Difference  in  yield  between  Rural  New-Yorker  potatoes, 
irrigated  and  not  irrigated,  in  1897. 

and  given  flat  cultivation  after  every  rain,  or  oftener,  until  the 
vines  were  so  large  as  nearly  to  cover  the  ground,  when  they  were 
hilled  with  a  double  shovel  plow  drawn  through  the  center  of  each 
row,  forming  ridges  about  5  inches  high,  the  nose  of  the  shovel 
passing  about  3  inches  below  the  surface  of  the  ground. 


174  Irrigation    and    Drainage 

The  amounts  of  rainfall  and  of  water  applied  by  irrigation  are 
given  in  the  table  below : 

i Rainfall >  ' Watev  of  irrigation » 

1896  1897  1896  1897 

INCHES  INCHES  INCHES  INCHES 

May....  6.11  .51  May May 

June 2.25  4.03  June June 

July....  3.42  1.79  July  10....  2.15  July  20....  2.45 

Aug....  2.43  3.7  July  21....  2.15  Aug.  18  . . .  2.45 

Sept....  3.73  1.73  Aug.  3....  2.15  Sept.  8....  2.45 

Aug.  10  ...     2.15 

Sept.  3....     2.15 

Sum.     17.94  11.76  10.75  7.35 

The  distribution  of  the  rainfall  during  the  season  can  be 
learned  from  the  table  given  on  page  108.  It  will  be  seen  that  in 
1896  the  irrigated  potatoes  had  10.75  inches,  and  in  1897  7.35 
inches,  more  water  than  the  potatoes  grown  under  the  natural 
rainfall  conditions. 

These  differences  in  the  amount  of  water  produced  differences 
of  yield,  which  are  shown  below  in  the  table,  and  graphically  to 
the  eye  in  Figs.  26,  27  and  28.  To  eliminate  the  effects  of  varying 
soil  conditions,  the  water  was  applied  to  alternate  groups  of  6  to 
10  rows,  with  corresponding  intervening  groups  of  rows  which 
received  no  water.  There  were  16  of  these  plots  in  1896  and  22 
in  1897,  making  38  trials  in  all,  in  which  there  were  grown  a  total 
of  555  bushels  of  potatoes,  or  33,304.4  pounds. 

Table  vhowing  yield  per  acre  of  potatoes  irrigated  and  not  irrigated  in 
Wisconsin 

RURAL  NEW- YORKER 

Irrigated .          , Not  irrigated . 

Large  Small  Large  Small 

BU.  BU.  BU.  BU. 

1896 382  12.2  280.3  10.2 

1897 365.8  9.1  239.6  9.7 

BURBANK  TYPB 

1896 220  22.7  141.5  16.2 

1897 302  18.8  184.8  19.7£ 

Mean 317.5  15.2  211.6  14 

Difference 105.9  1.8 


Increase    of   Cabbage    Crop    by    Irrigation        175 

There  is  thus  shown  a  difference  of  105.9  bushels  of  merchant- 
able tubers  per  acre,  as  an  average  of  two  years,  in  favor  of  the 
larger  water  supply. 


EFFECT     OF     SUPPLEMENTING      THE     RAINFALL     IN     WIS- 
CONSIN   FOR    CABBAGE    CULTURE 


In  the  work  with  cabbage,  the  rows  were  set  30  inches  apart, 
and  in  half  of  the  area  the  plants  were  set  15  inches  apart  in  the 
row,  and  on  the  balance  of  the  area  30  inches  apart,  of  the  variety 
Fottler's  Drumhead.  There  were,  in  all,  22  alternating  plots  of  6 
rows  each,  one  half  irrigated  and  the  balance  not.  The  soil  was 
a  rather  heavy  clay  loam,  which  had  been  heavily  manured  the 
previous  year,  and  had  grown  a  crop  of  cabbage  and  cauliflower, 
but  nothing  was  added  this  season.  Flat  and  frequent  cultivation 
was  given  until  the  plants  were  large  and  nearly  covered  the  ground, 
July  21,  when  the  first  irrigation  was  made,  the  irrigated  rows 
being  furrowed  the  same  as  the  potatoes,  and  not  again  disturbed. 

The  mean  weight  of  heads  produced  under  the  two  treatments 
was  as  follows  : 


Thin  planting 

Irrigated  Not  irrig. 

LBS.  LBS. 


Firm  heads  . 
Loose  heads 


7.0 


B.8D 

4.3I5 


Thick  planting , 

Irrigated  Not  irrig. 

LBS.  LBS. 

5.13  4.46 

3.23  2.39 


The  weight  of  the  heads  dressed  for  market,  computed  for  one 
acre,  was  as  expressed  in  the  following  table: 


iin  plantini 


Thick  plantinj 


Irrigated    Not  irrig.      Diff.         Irrigated      Not  irrig.      Diff. 


LBS. 

Firm  heads 30,610 

Loose  heads 6,227 


Total 36,837 

Leaves  and  stumps . .  42,730 

Grand  total....  79,567 

Tons...  39.78 


LBS. 

LBS. 

LBS. 

LBS. 

LBS. 

29,480 
4,624 

1,130 
1,603 

46,590 
7,688 

40,100 
5,943 

6,490 
1,745 

34,104 
39,220 

2,733 
3,510 

54,278 
64,100 

46,043 
57,630 

8,235 
6,470 

73,324 

6,243 

118,378 

103,673 

14,705 

36.66 

3.12 

59.19 

51.84 

7.35 

176 


Irrigation    and    Drainage 


The  amount  of  water  given  to  this  crop  was  8.245  inches,  in 
four  applications,  July  21,  Aug.  3  and  10,  and  Sept.  3,  2.061 
inches  being  applied  each  time. 

The  difference  between  equal  numbers  of  rows  of  cabbage 
irrigated  and  not  irrigated  is  shown  in  Fig.  29.  Were  the  cabbage 
grown  for  green  fall  and  early  winter  feed  for  stock  it  will  be  seen 
that  the  close  setting  gives  a  difference  in  favor  of  irrigation 


Fig.  29.    Difference  in  yield  between  cabbage,  irrigated  and  not  irrigated 

amounting  to  7.35  tons  per  acre.  This  occurred,  too,  under  con- 
ditions in  which  the  plots  not  irrigated  received  considerable 
water  from  seepage  from  the  heavy  irrigation  of  a  piece  of 
meadow. 

The  same  season  that  these  experiments  were  made  with  cab- 
bage, similar  ones  were  conducted  with  mangold -wurzels  and  with 
turnips.  But  while  a  good  yield  of  beets  was  secured  per  acre, 
namely,  15.7  tons,  there  was  only  18  pounds  difference,  the  six 
rows  of  irrigated  mangolds  yielding  5,100  pounds  and  those  not 
irrigated  5,082  pounds.  The  turnips,  on  account  of  a  blight, 
did  nothing  under  either  treatment,  and  the  same  was  true  foi 
rape. 


THE    EFFECT    OF    SUPPLEMENTING    THE    RAINFALL    WITH 
IRRIGATION    ON    THE    YIELD    OF     CORN 

During  four  consecutive  years  we  have  grown  corn  upon  one 
area,  irrigating  a  part  and  reserving  another  part  not  irri- 
gated, as  a  check.  The  soil  of  this  plot  is  medium  clay  loam 


Increase   of  Corn    Crop   by   Irrigation          177 

Just  before  beginning  the  experiments  it  had  been  in  clover,  and 
was  dressed,  with  farmyard  manure  at  the  rate  of  44  loads  per  acre 
before  plowing,  in  the  spring  of  1894.  Since  this  time  it  had  re- 
ceived no  manure  or  fertilizers  of  any  kind,  one  object  of  the 
experiment  being  to  ascertain  whether  under  irrigation  the  land 
rapidly  deteriorates  in  productiveness. 

Each  season  the  corn  has  been  planted  very  close,  in  rows  30 
inches  apart  and  in  hills  15  inches  in  the  row,  working  upon  the 
hypothesis  that  when  an  abundance  of  water  is  supplied  more 
plants  may  be  grown  upon  the  same  area,  the  hypothesis  having 
been  suggested  by  the  large  yields  universally  secured  in  the 
experimental  cylinders. 

The  number  of  stalks  in  a  hill  has  varied,  but  usually  as 
many  as  3  to  5  stalks  have  been  allowed  to  mature.  Both  flint 
and  Pride  of  the  North  dent  corn  have  been  grown  each  year, 
and  one  season  a  part  of  the  area  was  planted  with  rows  36 
instead  of  30  inches  apart.  The  table  which  follows  gives  the 
yields  of  water-free  matter  per  acre,  together  with  the  rainfall  of 
the  growing  season  and  water  added  by  irrigation: 


Not  Irrigated 

Irrigated 

Difference 

Kind 

Water 

Dry 

Water 

Dry 

Water 

Dry 

of  corn 

used 

matter 

used 

matter 

used 

matter 

INCHES 

LBS. 

INCHKS 

LBS. 

INCHES 

LBS. 

1894 

Flint 
Dent 

8.15 

7,916 
7,426 

1R.76 

11,080 
9.625 

8.61 

;ut>4 

2,199 

1895 

Flint 
Dent 

4.48 

2,458 
8,144 

31.08 

10,048 
11,125 

26.6 

7,590 
7,981 

1896 

Flint 
Dent 

15.02 

8,129 
8,450 

27.07 

10,320 
10,280 

12.03 

2,191 
1,830 

1897 

Flint 
Dent 

10.66 

6,766 
6.853 

16.36 

8,571 

8,438 

5.7 

1,805 
1,585 

It  will  be  seen,  from  the  data  of  this  table,  that  there  has  been 
during  the  four  years  a  mean  gain  due  to  the  increased  water  sup- 
ply amounting  to  3,543  pounds  of  water-free  substance,  while  the 
mean  yield  under  the  season's  rainfall  with  the  best  of  tillage  has 
been  6,393  pounds  per  acre,  or  an  increase  of  55  per  cent.  The 
smallest  mean  gain  realized  in  any  year  has  been  24.9  per  cent 
and  the  largest  278  per  cent. 


178 


Irrigation    and    Drainage 


In  Fig.  30  is  shown  the  difference  between  the  corn  on  land 
irrigated  and  not  irrigated  in  1895,  when  there  was  the  largest  ob- 


Fig.  80.     Difference  in  yield  between  maize,  thickly  seeded,  irrigated 
and  not  irrigated,  in  a  dry  season. 

served  difference  in  the  yield.  Fig.  25  shows  the  difference  where 
the  rows  are  44  inches  apart  instead  of  30  inches,  as  in  the  former 
ease. 

THE    EFFECT     OF    SUPPLEMENTING    THE    RAINFALLL    WITH 
IRRIGATION     ON    THE     YIELD     OF     CLOVER     AND     HAY 

The  crop  of  hay  is,  perhaps,  the  one  above  all  others  among 
the  general  farm  crops  which  may  be  made  to  respond  most  effec- 
tively to  irrigation  in  humid  climates.  Indeed,  it  is  the  chief  one 
in  Europe  which  has  been  grown  by  irrigation  north  of  Italy 


Increase   of  Hay    Crop    by    Irrigation          179 

and  southern  France.  Reference  has  already  been  made  to 
water  meadows. 

We  have  shown  in  another  place  that  the  average  yield  of  hay 
per  acre  in  thirteen  states  in  this  country  was,  for  1879,  only  1.1 
tons.  It  is  true,  however,  that  good  soils,  well  managed,  may  be 
made  to  yield  most  years  an  average  of  possibly  1.5  tons  per  acre. 
There  will  be  seasons,  however,  for  these  soils  when  the  yield  will 
drop  back  to  1  ton  per  acre.  ^  Again,  those  seasons  are  rare  for 
most  soils  in  the  United  States  which  will  permit  them  to  produce 
three-fourths  of  a  ton  of  hay  per  acre  as  a  second  crop  without 
irrigation. 

Our  experiments  in  irrigating  clover  for  a  second  crop  gave 
1.798  tons,  2,035  tons,  and  1.773  tons  of  hay,  containing  15  per 
cent  of  moisture,  for  the  years  1895,  1896,  and  1897  respectively. 
In  irrigating  the  first  crop  of  clover,  the  yields  have  been  4.01  tons 
per  acre,  in  a  case  of  sub -irrigation  through  tile  drains  in  1895, 
and  2.671  and  2.65  tons  in  1897,  which  were  surface  irrigated, 
making  an  average  for  the  two  crops  of  4.979  tons  of  hay  per  acre 
so  thoroughly  cured  as  to  contain  85  per  cent  of  dry  matter. 
These  results,  it  should  be  Understood,  are  derived  by  making  an 
actual  determination  of  the  dry  matter  in  each  crop  and  comput- 
ing the  weights  of  hay  from  the  amount  of  dry  matter. 

It  will  be  observed  that  these  yields  are  more  than  four  times 
the  mean  yield  of  the  thirteen  states  cited  in  another  place.  In 
addition  to  the  first  and  second  crops,  there  has  been  each  time  an 
excellent  third  crop,  which  could  be  used  for  fall  pasture,  and 
easily  double  in  quantity  the  non- irrigated  fall  feed  of  the  best 
seasons.  Fig.  31  is  a  view  of  the  second  crop  of  1895,  the  third 
crop  on  the  same  ground,  giving  pasture  for  58  adult  sheep  31  days 
on  3.2  acres. 

A  CROP  OF  BARLEY  AND  A  CROP  OF  HAY  THE 
SAME  SEASON 

In  the  spring  of  1897  we  seeded  a  piece  of  ground  to  clover 
with  barley,  irrigating  a  part  of  the  barley  twice,  both  to  see  what 
the  effect  would  be  upon  the  yield  of  barley  and  upon  the  clover 


180 


Irrigation   and    Drainage 


which  had  been  sown  with  it.  It  so  happened  that  immediately 
after  each  time  of  irrigating  the  barley  a  good  rain  followed,  and 
the  difference  in  yield  of  grain  and  straw  per  acre  was  small,  as 

stated  below: 

Irrigated        Not  irrigated        Difference 

Air-dry  straw-lbs 5,735  5,133  602 

Air-dry  grain— bu 45.67  44.25  1.42 

But  the  effect  on  the  clover  was  very  marked.     In  order  to 
bring  up  the  clover  on  the  areas  not  irrigated,  the  ground  was 


Fig.  31.    Second  crop  of  clover  hay  on  irrigated  ground. 

irrigated  immediately  after  cutting  the  barley,  July  23.  Two  other 
irrigations  were  given  the  ground,  and  as  a  result  there  was  a  crop 
of  mixed  clover  and  barley,  cut  on  Sept.  22,  which  equaled  1.36 
tons  of  hay.  The  barley  cut  with  the  clover  resulted  from  the 
germination  of  seed  which  shelled  in  harvesting  the  grain,  and 
was  just  heading  out  when  it  was  cut  to  put  into  the  silo. 

It  is  very  evident,  from  these  results,  that  it  will  be  possible 


Increase  of  Small  Fruit  Crop  by  Irrigation      181 

to  seed  clover  with  either  oats  or  barley,  and  by  cutting  the  first 
crop  early  for  hay  and  then  irrigating,  a  second  crop  of  hay  equal 
at  least  to  one  ton  per  acre  may  usually  be  taken,  besides  making 
it  certain  that  a  good  sta,nd  of  clover  is  secured  for  the  next  year. 

THE    EFFECT     QF     SUPPLEMENTING     THE     RAINFALL    FOE 
STRAWBERRIES 

The  strawberry  is  a  crop  which  will  respond  in  a  marked  man- 
ner to  judicious  applications  of  water  in  most  parts  of  the  United 
States  suited  to  its  growth,  as  the  results  secured  at  this  station 
by  Professor  Goff  clearly  show.  His  yields  per  acre  were : 

Irrigated  Not  irrigated  Difference 
BU.                     BU.  BU. 

1894 214.6  109.3  105.3 

1895...  272.9  32.2  240.7 


Mean 243.8  70.8  173 

It  is  here  seen  that  the  irrigated  yield  was  more  than  three 
times  as  large  as  that  under  natural  rainfall  conditions  ;  and  not 
only  was  the  yield  this  much  larger,  but  the  quality  of  the  berries 
was  also  improved  by  the  irrigation,  they  being  larger  and  more 
salable. 

While  we  are  able  to  cite  no  critical  data  regarding  the 
advantage  of  irrigation  in  humid  climates  on  blackberries,  rasp- 
berries, currants  and  gooseberries,  the  unquestioned  fact  that  these 
do  very  frequently  suffer  severely  from  the  effects  of  drought 
leaves  no  room  to  doubt  that  these,  like  the  strawberries,  would 
be  greatly  benefited  by  irrigation  in  very  many  seasons. 


CLOSER   PLANTING  MADE   POSSIBLE   BY   IRRIGATION 

It  lias  been  pointed  out  that  in  sub -humid  climates 
the  limiting  factor  which  determines  the  number  of 
plants  which  may  develop  to  advantage  in  a  given  soil 
is  the  amount  of  available  moisture  ;  but  that  in  coun- 


182  Irrigation   and    Drainage 

tries  where  there  is  an  abundant  and  timely  distribution 
of  rain,  or  where  irrigation  is  practiced,  the  number 
of  plants  per  acre  may  be  so  far  increased  that  the 
limiting  factors  become  the  available  plant-food  stored 
in  the  soil,  the  amount  of  sunshine  which  falls  upon 
the  area,  or  the  circulation  of  air  about  the  assimilat- 
ing foliage. 

It  is  very  evident  that  were  the  amount  of  available 
water  for  crop  production  the  only  factor  which  de- 
termines the  number  of  plants  which  can  be  grown  per 
unit  area,  the  methods  of  irrigation  would  make  it  pos- 
sible to  greatly  increase  the  yield  of  almost  any  crop 
in  the  most  humid  of  climates.  But  there  are  many 
limiting  factors  which  set  rigid  bounds  beyond  which 
irrigation  may  not  pass. 

Sufficient  breathing  room  in  the  soil. — Since  the  roots 
of  all  cultivated  plants  demand  free  oxygen  in  the  soil 
for  their  respiration,  and  since  not  only  the  possible 
quantity  of  free  oxygen  in  the  soil,  but  the  rate  at 
which  it  may  be  supplied,  decreases  as  the  quantity  of 
water  in  the  soil  increases,  and  since  the  closer  the 
plants  are  set  upon  the  ground  the  more  densely  crowded 
must  the  roots  be  in  the  soil,  and  the  more  rapid  must 
be  the  interchange  of  gases  between  the  soil  and  the 
air  above  in  order  to  meet  the  increased  demands  for 
growth,  it  is  plain  that  the  demand  for  free  oxygen  in 
the  soil  sets  a  rigid  limit  beyond  which  closer  planting 
must  not  be  pushed. 

It  must  be  kept  ever  in  mind  that  the  soil  is  like  a 
very  poorly  ventilated  assembly  hall,  which  may  easily 
be  so  crowded  as  not  only  to  produce  discomfiture  to 


Factors   Limiting    Closeness   of  Planting        183 

its  occupants,  but  disaster  as  well.  Nor  do  the  roots 
of  the  plants  which  occupy  the  field  constitute  the  only 
demand  for  free  oxygen  in  the  soil,  for  the  various 
fermenting  germs  which  transform  humus  into  avail- 
able nitrates  must  have  free  oxygen,  or  the  all- 
important  nitric  acid  cannot  be  made,  and  the  farm- 
yard manures  applied  to  the  soil  must  lie  there  unal- 
tered and  of  no  avail. 

Soil  temperature  reduced  by  too  close  planting. — Then, 
again,  too  heavy  verdure  above  the  soil  so  completely 
absorbs  the  heat  from  the  surrounding  air  and  dissi- 
pates it  again  into  space,  that  the  soil  temperature  can- 
not rise  high  enough  to  produce  the  maximum  rate 
of  solution  and  production  of  plant -food,  nor  the 
maximum  root  pressure  so  essential  to  sending  the  dis- 
solved and  prepared  food  into  the  foliage  above,  where 
assimilation  takes  place ;  while  the  humus  'and  ma- 
nure-fermenting germs  themselves  must  work  the  slower 
the  lower  the  soil  temperature  is  after  it  falls  below 
98°  F.  It  is  true  that  available  nitrates  may  be  applied 
to  the  soil  direct,  and  other  of  the  ash  ingredients  in 
soluble  form  may  be  added,  or  the  soil  may  receive 
thorough  and  repeated  tillage  before  the  crop  is  put 
upon  it,  and  thus  a  supply  in  advance  be  generated, 
which  leaves  more  of  the  oxygen  and  of  the  soil  warmth 
for  the  service  of  the  roots;  but  neither  of  these  con- 
ditions can  be  attained  except  at  added  cost. 

The  sunshine  itself  is  limited. — Even  when  we  come 
to  the  item  of  sunshine  itself,  it  is  easy  to  so  increase 
the  number  of  plants  that  not  enough  sunshine  can  be 
absorbed  to  produce  normal  growth,  and  a  diminisfied 


184  Irrigation   and    Drainage 

yield  or  inferior  quality  results.  The  taller  the  plants 
which  are  brought  togethe-r,  the  farther  apart  as  a 
rule  must  they  be  placed,  in  order  that  sufficient  sun- 
light for  the  best  results  can  be  had.  The  flint  varie- 
ties of  maize  are  readily  grown  closer  together  than  the 
smaller  of  the  dent  varieties,  and  these,  in  their  turn, 
may  stand  closer  on  the  ground  than  the  large  southern 
varieties. 

Neither  the  starches  nor  the  cellulose  out  of  which 
plant  tissues  are  built  can  be  properly  organized  and 
laid  down  in  too  feeble  a  light,  for  its  actinic  power  is 
demanded  to  accomplish  this  work,  just  as  it  is  in  pho- 
tog^aphy.  When  it  is  remembered  that  an  instanta- 
neous exposure  of  a  plate  in  the  bright  sunshine  may 
accomplish  more  chemical  change  in  the  negative  than 
can  be  done  in  two  minutes  in  the  diffused  light  of  a 
well-lighted  room,  it  can  be  readily  understood  that  the 
work  of  assimilation  in  the  lower  leaves  in  close  plant- 
ing must  be  greatly  enfeebled. 

It  is  for  this  reason,  apparently,  that  ears  will  not 
form  on  stalks  of  maize  planted  too  closely,  and  that 
they  form  more  abundantly  in  closer  planting  on  the 
small,  low  varieties  than  on  those  which  are  taller. 

It  is  for  the  same  reason,  too,  that  too  closely 
planted  crops  of  almost  any  kind  have  weak  stems  and 
are  unable  to  stand  up  well,  often  lodging  ;  neither  the 
starches  for  the  kernels,  in  the  former  case,  nor  the 
cellulose  in  the  latter  for  the  building  of  the  frame- 
work, are  able  to  form  rapidly,  and  abnormal  growth 
is  the  result.  Whoever  has  entered  and  emerged  from 
a  tunnel  has  been  surprised  at  the  short  distance  from 


Factors   Limiting    Closeness   of  Planting        185 

the  mouth  at  which  the  tunnel  becomes  dark ;  the  re- 
peated reflections  from  the  walls  soon  absorb  completely 
all  of  the  light  which  enters.  It  is  the  same  way  with 
close  planting,  especially  if  the  individuals  are  tall,  the 
upper  parts  of  the  tall  plants  absorbing  just  as 
much  light  as  the  same  length  of  shorter  plants,  hence 
leaving  less  light  to  work  in  the  foliage  and  stems  of 
the  lower  parts. 

Possible  insufficiency  of  carbon  dioxide  in  close 
planting. — When  a  crop  like  maize,  which  grows  so 
tall  and  spreads  its  leaves  so  broadly,  is  planted  closely 
it  seems  not  impossible  that  on  days  of  exceptionally 
bright  sunshine  and  when  very  little  wind  is  moving, 
there  may  be  such  rapid  consumption  of  carbon  dioxide 
from  the  air  as  to  so  far  reduce  its  amount  that  an 
inadequate  supply  may  actually  reach  the  plants. 

It  has  been  shown  on  a  preceding  page  that  a  clover 
crop  yielding  4,500  pounds  of  hay  per  acre  demands 
for  its  carbon  all  of  the  carbon  dioxide  contained  in  a 
layer  of  uniform  density  covering  the  acre  3,503  feet 
deep.  But  in  the  case  of  a  corn  crop,  in  which  the  yield 
of  water -free  matter  has  exceeded  14,000  pounds,  the 
volume  of  air  required  to  give  up  its  carbon  dioxide 
must  have  exceeded  that  above  more  than  threefold, 
or  a  column  of  uniform  density  exceeding  10,509-  feet 
in  height.  Fully  80  per  cent  of  this  assimilation  of 
carbon  by  the  corn  plant  must  take  place  in  the  50 
days  following  July  1.  Imagine,  if  you  will,  a  field  of 
corn  160  rods  long  and  1  rod  wide,  enclosed  by  a 
transparent  structure  having  the  same  floor  space  and 
rising  to  a  height  of  10,000  feet,  so  as  to  enclose  the 


186  Irrigation   and    Drainage 

volume  of  air  stated  above.     Now,  let  this  structure  be 
provided  with  a  ceiling  without  weight,  which  is  lifted 
as  the  corn  grows  in  height.     This  imaginary  ceiling  is 
to  separate  the  volume  of   air  stored  above  from  the 
moving   air    in    the   corn   field    below,    and    to    admit 
through   a  changing   doorway   a  steady  stream  whose 
cross -section   is  that  of  the  transverse  section   of   the 
room  occupied   by  the  corn.     How  rapidly  must   this 
stream  of  air  flow  in  order  to  discharge  80  per  cent  of 
the  volume  contained  in  the  structure  in  the  sunshine 
hours  of  50  days  ?     The  maximum  number  of  sunshine 
hours  in  the  latitude  of  New  York  is  about  623.     If  we 
suppose  the  corn  to  be  1  foot  high  July  1  and  10  feet 
high  on  August  19,  the  ceiling  to  have  risen  uniformly 
in  the  meantime,  so  that  the  stream  of  air  increased  in 
depth  from  1  foot  to  10  feet  ;   then,  taking  the  mean 
depth  of  the  moving  air  current  at  5.5  feet,  its  hourly 
velocity,    in  order   to  convey  the    80    per  cent   of   air 
across  the  field,  must  have  been  1.167   miles.     On  the 
other  hand,  let  us  suppose  the  corn  field  to  be  square, 
so  that  the  area  is  as  compact  as  possible,   so  that  a 
stream  of  air  now  about  13  rods  wide  instead  of  1  is 
passing  across  it.     The  required  velocity  to  convey  the 
80  per  cent  of  air  across  the  field  is  now  only   one- 
ninth  of   a  mile  per  hour  and   less  than   10  feet   per 
second.     Since  the  yield  of  dry  matter  per  acre  is  the 
largest  we  have  yet  raised  under  field  conditions,  and 
the  computed  velocities  above  are  so  small,  it  does  not 
appear  likely  that  an  insufficiency  of  carbon  dioxide  in 
the  air  can  ever   be  a   serious   limiting  factor   to  the 
closeness  of  planting  when  irrigation  is  practiced. 


Maximum  Limit  of  Productiveness  for  Maize    187 


MAXIMUM     LIMIT     OF     PRODUCTIVENESS     FOR     MAIZE 

In  order  that  some  idea  of  the  possible  maximum  yields  of 
maize  per  acre  might  be  formed,  we  have  gone  into  the  field, 
when  the  corn  was  mature,  and  selected  40  of  the  largest  stalks 
bearing  the  largest  ears  we  could  find,  and  have  determined  the 
water-free  matter  in  both  ears  and  stalks,  in  order  to  secure  a 
measure  of  the  mean  maximum  adult  plant  to  use  as  a  basis  of 
computation  for  this  problem.  The  results  were  these: 

40  stalks  of  Pride  of  the  North  maize  contained  15.6  Ibs.  water-free  substance. 

40  ears  16.1    " 

40      "        "        "          "  "          13.7    "  shelled  corn. 

40      "        "        "          "  2.4    "  cobs. 

Using  these  data,  we  may  compute  the  maximum  possible 
yields  per  acre  where  different  degrees  of  closeness  of  planting  are 
adopted,  supposing  that  every  plant  produces  a  maximum-sized 
stalk,  bearing  a  maximum  ear  corresponding  with  the  data  above. 

Then  maize  planted  in  hills  4  feet  x  4  feet,  and  4  stalks  in  a 
hill,  or  in  drills  4  feet  x  1  foot,  might  yield  8,630  pounds  dry  mat- 
ter, 3,730  pounds  kiln-dried  shell  corn,  equal  to  66.61  bushels,  or 
73.27  bushels  when  containing  10  per  cent  of  moisture. 

With  maize  planted  in  hills  44  inches  x  44  inches,  4  stalks  in 
a  hill,  or  44  inches  x  11  inches  in  drills,  the  maximum  yield  per 
acre  would  be  10,270  pounds  dry  matter,  4,439  pounds  kiln-dried 
shelled  corn,  equal  to  79.27  bushels,  or  87.2  when  containing  10 
per  cent  of  moisture. 

Maize  planted  42  inches  x  42  inches,  4  stalks  in  a  hill,  or  in 
drills  42  inches  x  10.5  inches,  might  yield  11,270  pounds  of  water- 
free  matter  and  4,871  pounds  of  kiln-dried  shelled  corn,  equal  to 
87  bushels,  or  to  95.7  bushels  when  containing  10  per  cent  of 
moisture. 

Maize  planted  36  inches  x  36  inches,  4  stalks  in  a  hill,  or  in 
drills  36  inches  x9  inches,  might  yield  15,340  pounds  of  dry  matter 
and  6,600  pounds  of  kiln -dried  shelled  corn,  equal  to  118.4 
bushels,  or  to  130.27  bushels  when  containing  10  per  cent  of  water. 


188  Irrigation   and    Drainage 

Maize  planted  30  inches  x  30  inches,  4  stalks  in  a  hill,  or  30 
inches  x  7.5  inches  in  drills,  might  yield  22,090  pounds  of  dry 
matter  per  acre  and  9,574  pounds  of  kiln -dried  shelled  corn, 
equal  to  170.4  bushels,  or  187.44  bushels  containing  30  per  cent 
of  water. 

Maize  planted  30  inches  x  15  inches,  4  stalks  in  a  hill,  or  in 
drills  30  inches  x  3%  inches,  might  yield,  if  every  stalk  equaled  the 
average  of  the  40  stalks  cited  above,  44,180  pounds  of  dry  matter 
per  acre  and  19,148  pounds  of  kiln-dried  shelled  corn,  equal  to 
340.8  bushels,  or  374.88  bushels  when  containing  10  per  cent  of 
moisture. 

Some  of  the  yields  here  computed  have  been  realized  under 
field  conditions,  but  the  higher  ones  never  have  been  and  prob- 
ably never  can  be,  under  any  system  of  culture  us  a  single  crop. 
In  our  experimental  work  with  the  large  cylinders,  the  largest 
yield  we  have  obtained  was  34,730  pounds  of  water-free  sub- 
stance when  4  stalks  occupied  a  soil  space  of  1.767  square  feet, 
which  is  closer  planting  than  the  closest  given  above,  namely 
rows  30  inches  apart,  with  corn  in  drills,  stalks  1%  inches  apart. 

The  largest  yield  we  have  secured  in  the  field  was  on  an 
area  of  irrigated  ground  measuring  about  2,400  square  feet,  where 
the  amount  of  dry  matter  per  acre  was  29,000  pounds,  or  14.5 
tons.  In  this  case,  the  corn  was  planted  in  rows  30  inches  apart 
and  in  hills  15  inches  apart,  with  3  to  5  stalks  in  a  hill.  The  area 
was  not  an  isolated  plot,  but  was  a  selected  spot  in  an  irrigated 
area  where,  on  account  of  a  sag  in  the  ground,  the  corn  had 
received  more  than  the  average  amount  of  water.  The  closeness 
of  planting  in  this  case  was  equivalent  to  drilled  rows  with  1  stalk 
every  3%  inches,  which  is  the  same  as  the  closest  given  above, 
but  the  corn  was  a  variety  of  flint  maize,  not  dent. 

THE    OBSERVED    YIELDS     OP     MAIZE    PER    ACRE     PLANTED 

IN    DIFFERENT    DEGREES     OF    THICKNESS    AND    WITH 

DIFFERENT    AMOUNTS     OF    WATER 

It  has  been  possible,  with  our  irrigation,  to  make  a  direct  test 
of  the  influence  of  the  amount  of  water  on  closeness  of  planting 


Maximum    Limit   of  Production  for   Maize      189 

maize,  and  thus  to  demonstrate  whether,  with  the  aid  of  irriga- 
tion, it  will  be  possible  in  humid  climates  to  secure  larger  yields 
by  planting  closer  together. 

The  problem  this  year  has  been  tested  with  two  varieties  of 
maize,  Pride  of  the  North,  and  a  white  dent  of  unknown  name. 
Each  has  been  planted  in  rows  44  inches  apart  and  in  hills  15 
inches  in  the  row.  The  white  dent  was  thinned  to  4  stalks,  3 
stalks,  2  stalks,  and  1  stalk  in  a  hill,  and  the  Pride  of  the  North 
to  3  stalks,  2  stalks,  and  1  stalk  in  a  hill.  It  was  found,  after  the 
stalks  had  attained  some  size  after  thinning,  that  the  white  dent 
threw  out  1  and  sometimes  2  suckers  where  it  had  been  thinned 
to  1  stalk.  These  were  allowed  to  stand,  rather  than  incur  the 
risk  of  introducing  greater  irregularities  which  would  be  unknown. 
But  few  of  these  suckers  matured  ears,  and  hence  their  effect  has 
been  to  increase  the  amount  of  stalk  in  proportion  to  the  ear,  and 
possibly  even  to  reduce  the  weight  of  ears,  particularly  on  the 
ground  not  irrigated.  The  Pride  of  the  North  was  planted  on 
ground  from  which  hay  had  been  cut  three  consecutive  years,  and 
in  which  a  fair  amount  of  clover  was  maintained,  the  land  having 
been  irrigated.  The  white  dent  was  grown  upon  ground  from 
which  two  crops  of  cabbage  had  been  taken,  and  which  had  been 
irrigated  for  both  crops.  Preparatory  to  planting  the  first  crop  of 
cabbage,  after  turning  under  the  clover  sod,  the  ground  had  been 
given  a  dressing  of  partly  rotted  stable  manure  amounting  to  68 
tons  per  acre.  In  addition  to  this,  a  mixture  of  commercial  fer- 
tilizers consisting  of  157  pounds  of  bone  meal,  25  pounds  Armour's 
"all  soluble"  fertilizer  and  6  pounds  of  nitrate  of  soda  was  sown 
broadcast  upon  the  ground  Aug.  16.  Neither  manure  nor  fertil- 
izers of  any  kind  were  given  to  the  soil  of  either  piece  for  the 
season  the  corn  was  grown  nor  the  year  before. 

In  both  cases  the  corn  was  harrowed  before  coming  up,  and 
cultivated  twice  in  a  row  until  too  large  to  work  longer.  The 
several  areas  bearing  corn  of  different  degrees  of  thickness  were 
divided  into  three  sub-plots,  and  the  middle  one  in  each  case  was 
not  irrigated,  while  the  two  adjacent  ones  were. 

At  maturity  the  corn  was  husked,  and  the  amount  of  water- 
free  substance  in  both  ear  and  stalk  determined  in  each  case. 


190 


Irrigation   and    Drainage 


The  photo -engravings,  Figs.  32,  33,  34  and  35  (pages  192,  193), 
show  the  relative  amounts  of  corn  husked  from  each  plot  and  the 
areas  upon  which  these  were  grown,  while  in  the  table  below  are 
given  the  yields  per  acre: 

WHITE  DENT 


4  stalks  . 

/  iJ  stams  

<  &    SIH1K.S  

'  J.     OLtVIJi  

Dry 
matter 

Shelled 

Dry 
matter 

Shelled 

Dry 

matter 

Shelled 

Dry 

matter 

Shelled 

per  acre 

corn 

per  acre 

corn 

per  acre 

corn 

per  acre 

corn 

LBS. 

BU. 

LBS. 

BU. 

LBS. 

BU. 

LBS. 

BU. 

Corn 

Irrigated 

11,426 

53.44 

12,567 

63.23 

11,712 

66.01 

9,554 

49.53 

8,758 


30.38 


23.06 


9,126 


Corn  not  Irrigated 

39.45  7.931  48.66 


Difference  in  Yield 
3,441  23.78  3,181 


17.35 


7,354 


2,200 


10.5 


In  the  case  of  the  Pride  of  the  North,  the  corn  was  planted 
3  stalks,  2  stalks,  and  1  stalk  in  a  hill,  and  the  yields  in  this  case 
were  as  follows  : 

PRIDE  OP  THE  NORTH  DENT 


3  stalks 

Dry  matter  Shelled 

per  acre  corn 

LBS.  BU. 


12,300 
10,265 
2.035 


73.24 


45.20 


28.04 


2  stalks 

Dry  matter         Shelled 
per  acre  corn 

LBS.  BU. 

Corn  Irrigated 
11.350  69.62 

Corn  not  Irrigated 
9,328  47.79 

Difference 
2,022  21.83 


8,944 


8,536 


408 


Shelled 
corn 
BU. 


55.29 


52.65 


3.64 


It  will  be  seen  from  these  tables  that  the  yield  of  water- free 
substance  per  acre  was  largest  in  every  case  where  the  corn  was 
planted  3  stalks  in  a  hill  every  15  inches,  and  in  rows  44  inches 
apart.  It  is  a  significent  fact  that  this  is  true,  not  only  with  both 


Yields   of  Maize   with   Irrigation  191 

varieties  of  corn,  but  also  where  the  corn  was  irrigated  and  where 
it  was  not  irrigated.  It  will  be  seen,  further,  that  the  smallest 
yield  of  dry  matter  per  acre  was  produced  where  the  smallest 
amount  of  seed  was  used,  namely,  where  1  stalk  grew  every  15 
inches  ;  but  one-third  the  number  of  plants  produced  about  three- 
fourths  as  much  dry  matter  per  acre  as  did  the  larger 'number  of 
plants. 

It  must  be  understood,  however,  that  so  far  as  mere  water 
is  concerned,  the  thinnest  planting  had  decidedly  the  advantage, 
as  no  effort  was  made,  even  on  the  ground  irrigated,  to  make 
the  water  applied  proportional  to  the  number  of  plants  and,  there- 
fore, to  the  evaporating  surface.  Whether  making  the  amount 
of  water  proportional  to  the  number  of  plants  would  have  materi- 
ally increased  the  yields  of  the  'thicker  seeding,  is  a  problem 
which  awaits  demonstration.  Indeed,  we  do  not,  as  yet,  know 
that  the  thinnest  seeding  had  all  of  the  water  which  could  be  used 
to  advantage,  even  where  irrigation  was  practiced.  But  the  fact 
that  the  smaller  variety  of  maize,  Pride  of  the  North,  the  one 
which  produced  no  suckers,  and,  therefore,  the  one  which  more 
nearly  represented  1  stalk  every  15  inches,  only  gave  an  increase 
of  408  pounds  of  dry  matter  per  acre  for  the  7.642  inches  of  water 
added  by  irrigation  to  the  rainfall  of  10.66  inches,  appears  to  show 
that  this  corn  found  in  the  10.66  inches  of  rain  nearly  all  the 
water  it  could  use  to  advantage.  This  view  is  strengthened, 
also,  by  the  fact  that  the  theoretical  yield  of  dry  matter  per 
acre  for  the  maize,  computed  from  the  data  in  the  table  on 
page  187,  is  8,848  pounds,  only  312  pounds  more  than  was 
observed. 

Looking  at  the  yield  of  kiln-dried  shelled  corn  per  acre,  it 
will  be  seen  that  here  a  somewhat  different  relation  holds,  the 
largest  crop  with  the  white  dent  variety  being  secured  from  2 
stalks  in  a  hill  every  15  inches  ;  but  with  the  smaller  variety  of 
Pride  of  the  North  the  largest  yield  of  shelled  corn  coincided 
with  the  3  stalks  in  a  hill  where  irrigation  was  practi  ><ed  ;  but 
where  the  natural  rainfall  alone  produced  the  crop,  tlie  largest 
yield  was  associated  with  the  thinnest  seeding,  or  1  stalk  every 
15  inches  in  the  row.  It  is  a  noteworthy  fact,  too,  that  the  7.642 


192 


Irrigation   and 


inches  of  water  added  by  irrigation  only  increased  the  grain  yield 
3.64  bushels  per  acre  on  the  thinnest  seeding,  appearing  to  show 


Fig.  32.    Maize,  irrigated  and  not  irrigated,  four  stalks  in  a  hill, 
middle  section  not  irrigated. 

that  for  this  soil  and  rainfall  there  was  very  nearly  the  right  num- 
ber of  plants  in  the  row. 


Fig.  38. 


Maize,  irrigated  and  not  irrigated,  three  stalks  in  a  hill, 
middle  section  not  irrigated. 


In  regard  to  the  yields  from  the  thicker  seeding,  it  must  be 
said  that  it  does  not  follow  from  the  experiments  that  they  might 
not  have  been  quite  different  if,  in  the  application  of  water  to  the 
several  plots,  the  amounts  had  been  made  proportional  to  the 
number  of  plants  growing  on  the  area  ;  for  it  may  fairly  be  pre- 


Influence    of   Thick  '  Seeding   on    Development    193 

sumed,  until  positive  demonstration  shall  prove  to  the  contrary, 
that  in  case  there  was  a  deficiency  of  soil  moisture  for  the  thick 


Fig.  34.    Maize,  irrigated  and  not  irrigated,  two  stalks  in  a  hill, 
middle  section  not  irrigated. 

seeding,  a  larger  supply  would  have  increased  the  yield  of  shelled 
corn  as  well  as  the  total  amount  of  dry  matter. 


Fig.  35.    Maize,  irrigated  and  not  irrigated,  one  stalk  in  a  hill, 
middle  section  not  irrigated. 


INFLUENCE     OP     THICK     SEEDING     AND      IRRIGATION     ON 
THE    DEVELOPMENT    OF    THE    PLANT 

It  was  observed,  the  first  year  the  maize  was  planted  thickly 
and  irrigated,  that  the  corn  did  not  appear  to  develop  quite  nor- 

M 


194  Irrigation   and    Drainage 

mally,  the  tassels  coming  into  bloom  before  the  silks  were  ready  to 
receive  the  pollen,  and  it  looked  then  as  though  the  failure  to 
develop  the  normal  amount  of  ears  might  result  from  this  ab- 
normal development,  in  time,  of  the  staminate  and  pistillate 
flowers. 

The  facts  are  that  very  few  kernels  at  all  formed  on  the  non  - 
irrigated  dent  variety,  and  only  imperfect  ears  matured  on  the 
flint  variety  ;  while  on  the  irrigated  plots  very  many  ears  never 
filled  at  all,  and  with  many  of  those  which  did  develop  ears,  the 
kernels  did  not  cover  the  entire  cob,  it  being  very  often  observed 
that  no  kernels  at  all  formed  at  the  butt  of  the  ear,  and  sometimes 
none  even  half  way  to  the  tip.  Whether  the  thick  seeding  and 
rapid  growth  stimulated  by  irrigation  retards  the  development  of 
the  ear  by  shading,  or  overstimulates  the  maturing  of  the  tassel 
so  as  to  interfere  with  the  proper  fertilization,  cannot  be  decided 
from  data  yet  at  hand,  although  the  appearance  of  the  plants 
looks  very  much  as  though  such  an  abnormal  development  had. 
been  brought  about. 

The  nodes  of  the  stalks  are  certainly  lengthened  by  the  close 
planting  and  irrigation  practiced,  but  not  all  are  equally  affected. 
If  it  is  true  that  a  certain  intensity  of  sunlight  is  required  for  the 
proper  maturing  of  the  ear,  it  might  be  anticipated  that  the  effect 
of  the  shading  would  stimulate  a  greater  elongation  of  the  lower 
than  of  the  upper  nodes  of  the  stem,  thus  placing  the  ear  in  more 
intense  light.  To  ascertain  whether  any  such  change  as  this  had 
occurred,  measurements  were  made  of  40  stalks  of  irrigated  thick 
planting,  and  a  corresponding  number  of  plants  not  so  closely 
planted  and  not  irrigated,  of  Pride  of  the  North  dent,  with  the 
result  that  in  the  non-irrigated  corn  the  height  of  the  axil  bear- 
ing the  ear  was  46.82  per  cent  of  the  height  from  the  ground  to 
the  base  of  the  tassel  ;  while  that  of  the  irrigated  corn  was  55.2 
per  cent  of  the  height.  That  is  to  say,  the  ear  axil  in  the  thickly 
planted  irrigated  corn  was  raised  8.38  per  cent  nearer  to  the 
tassel. 

In  a  second  set  of  measurements,  with  the  same  variety  of 
corn,  the  height  of  the  axil  bearing  the  ear  was  49.44  per  cent  of 
the  height  of  the  tassel  above  the  ground,  while  under  the  condi- 


Influence   of   Thick    Seeding   on    Development    195 

tions  of  irrigation  the  height  of  the  axil  was  56.94  per  cent  of  the 
height  of  the  tassel,  making  a  difference  in  this  case  of  7.5  per 
cent  in  the  same  direction.  In  the  case  of  a  variety  of  flint  corn, 
however,  the  conditions  are  the  reverse  of  those  just  cited,  the  axil 
bearing  the  ear  being  41.16  per  cent  of  the  height  of  the  tassel, 
while  on  the  ground  irrigated  this  height  is  39.59  per  cent  of  the 
height  of  the  tassel  above  the  ground.  The  case  is,  therefore,  not 
without  exception  as  tending  to  show  that  the  deficiency  of  light 
modifies  the  plant  in  the  manner  pointed  out. 


CHAPTER    V 

THE  AMOUNT   4ND  MEASUREMENT  OF  WATER  REQUIRED 
FOR  IRRIGATION 

THERE  is  no  problem  of  greater  or  more  fundamen- 
tal importance  to  the  irrigator  than  that  which  deals 
with  the  amount  of  water  required  to  produce  paying 
yields  when  correctly  and  economically  handled  in  the 
production  of  crops  of  various  kinds.  The  problem  is 
an  extremely  complex  one,  which  has  received  as  yet 
very  inadequate  systematic  study  on  a  rational  basis, 
such  as  the  exigencies  of  the  case  demand. 


THE   MAXIMUM   DUTY   OF   WATER    IN    CROP 
PRODUCTION 

A  given  quantity  of  water  applied  to  the  soil,  either 
in  the  form  of  rain  or  by  methods  of  irrigation,  renders 
its  greatest  service  when  the  whole  of  it  is  taken  up  by 
the  roots  of  the  crop  growing  upon  the  ground,  leaving 
none  to  be  lost  by  surface  evaporation  or  by  percolation, 
unless,  indeed,  some  soil  leaching  is  indispensable  to 
unimpaired  fertility.  Were  it  practicable  to  establish 
and  maintain  field  conditions  of  culture  which  would 
insure  that  all  water  lost  from  the  soil  should  take 

(196) 


The   Duty   of   Water  197 

place  through  the  foliage  of  the  crop  being  fed,  then  a 
very  small  rainfall  during  the  growing  season,  and  a 
very  small  amount  of  water  added  by  irrigation,  would 
suffice  for  the  production  of  large  yields. 

In  other  words,  the  duty  of  water  in  crop  produc- 
tion is  determined  by  the  necessary  losses:  (1)  by 
transpiration  through  the  plant;  (2)  by  surface  evapo- 
ration from  the  soil ;  and  (3)  by  surface  and  under- 
drainage.  The  more  these  sources  of  loss  may  be  cur- 
tailed, the  larger  will  be  the  duty  of  water  in  both  arid 
and  humid  regions. 

In  countries  where  irrigation  must  be  practiced  in 
order  to  successfully  grow  crops,  skillful  management 
may  almost  wholly  prevent  loss  by  drainage,  and  loss 
by  surface  evaporation  from  the  soil  can  be  made 
relatively  very  small,  so  that  the  major  loss  may 
be  that  which  is  transpired  through  the  plant  itself. 
So,  too,  in  humid  climates,  the  losses  during  the  grow- 
ing season  by  both  drainage  and  surface  evaporation 
may  be  greatly  reduced  through  skillful,  intelligent 
practice. 

It  will,  therefore,  be  helpful,  in  forming  an  estimate 
of  the  possible  duty  of  water,  to  use  the  data  already 
presented  in  another  place  to  compute  the  minimum 
number  of  acre -inches  of  water  which  may  be  made  to 
produce  yields  of  different  amounts  under  the  condi- 
tions where  no  drainage  takes  place,  and  where  surface 
evaporation  is  made  as  small  as  it  can  well  be.  The 
results  of  such  a  calculation  are  given  in  the  table 
which  follows: 


198 


Irrigation   and    Drainage 


Table  showing  the  highest  probable  duty  of  water  for  different  yields  per  acre 
of  different  crops 


Bushels  per  acre  .  . 

15 

20 

30 

40 

50 

60       70 
of  acre-iii 

80 
dies 

100 

200 

300 

400 

•     Name  of  crop 

Least  number 

of  water 

Wheat 

4.5 
3.21 
2.35 
2.52 

1 

6 
4.28 
3.13 
3.36 
.41 

9 
6.42 
5.70 
5.04 
.62 

12 
8.56 
6.27 
6.72 

.83 

15 
10.7 
7.84 
8.4 
1.03 

18 
12.84 
9.40 
10.08 
1.24 

Barley 

14.98  .... 
10.98  lli.54 
11.7513.43 
1.45    1.65 

15.68 
16.77 
2.07 

Oats  
Maize 

Potatoes 

4.14 

6.2 

8.27 
20 

Tons  per  acre  

1 

2 

3 

4 

6 

8 

10 

12 

14 

16 

18 

Least  number  of  acre-inches  of  water 

Clover  hay, 
15  per  cent  water 
Corn  with  ears, 
15  per  cent  water. 
Corn  silage, 
70  per  cent  water. 

4.43 
2.08 
1.41 

8.85 
4.16 

2.82 

13.28 
6.24 
4.23 

17.7 
8.32 
5.6J 

26.55 
12.47 
8.46 

35.4 
16.61 
11.28 

44.25 
20.72 
14.1 

24.95 
16.92 

29.1 

19.74 

33.26 
22.56 

37.42 
25.38 

41.58 
28.2 

This  table  must  be  regarded  as  showing  the  mini- 
mum amounts  of  water  which  will  bring  the  crops 
named  to  full  maturity  so  as  to  produce  the  yields  speci- 
fied under  conditions  of  absolutely  no  loss  by  surface 
or  under -drainage,  and  where  the  evaporation  from  the 
soil  itself  is  as  small  as  it  can  well  be.  It  must  be 
further  understood  that  the  soil  at  seeding  time  already 
possesses  the  needful  amount  of  water  for  the  best  con- 
ditions, and  that  at  the  end  of  the  growing  season  it  is 
yet  so  moist  that  no  check  to  vigorous,  normal  growth 
has  occurred. 

The  figures  in  the  table  may,  therefore,  be  regarded 


Conditions  Modifying   Duty  of   Water  199 

as  the  nearest  estimate  now  attainable  of  the  minimum 
amount  of  water  the  irrigator  can  hope  to  deliver  to  his 
field  where  the  yields  there  stated  are  expected ;  and  if 
there  are  necessary  losses  in  bringing  the  water  to  the 
field,  either  by  seepage  or  evaporation  from  the  main  or 
lateral  ditches,  or  if  the  water  is  badly  handled,  so  that 
there  is  a  large  amount  of  percolation  ;  or,  again,  if 
unnecessary  losses  occur  through  lack  of  proper  tillage 
after  irrigation,  then  the  amounts  stated  in  the  table 
must  be  exceeded  by  the  amount  of  these  losses. 

CONDITIONS     WHICH     MODIFY     THE     AMOUNT     OF    WATER 
REQUIRED   IN   IRRIGATION 

Among  the  many  factors  and  conditions  which  increase  or 
diminish  the  duty  of  water  may  be  mentioned: 

1.  The  peculiarities  of  the  crop  grown.— From  what  has  been 
said  regarding  the  amount  of  water  required  for  a  pound  of  dry 
matter  and  for  yields  of  different  amounts  for  different  crops,  it 
will  be  evident  that  both  the  amount  of  water  required  by  a 
given  crop  and  the  frequency  with  which  it  should  be  applied  will 
depend  much  upon  the  crop  being  grown. 

This  variation  in  the  amount  of  water  required  by  different 
crops  depends  upon  many  factors,  some  of  which  are  not  well 
understood.  Both  the  number  and  size  of  the  breathing  pores  of 
the  green  parts  of  the  plant,  through  which  the  air  enters  and 
from  which  the  moisture  escapes,  may  be  expected  to  play  an 
important  part  in  determining  the  necessary  loss  of  water  which 
takes  place.  So,  too,  will  the  character  of  the  foliage  and  the 
habit  of  the  plant  as  influencing  the  amount  of  wind  movement, 
and  of  shade  over  the  soil  of  the  field,  effect  the  necessary  loss 
of  water  from  the  soil. 

In  illustration  of  the  influence  of  the  shade  offered  by  the 
crop  upon  the  loss  of  water  from  the  soil  may  be  cited  the  differ- 


200  Irrigation   and    Drainage 

ence  in  the  amount  of  water  in  the  soil  of  a  potato  field  where 
the  rows  extended  east  and  west,  thus  producing  a  shade  on 
the  north  side  of  each  row.  The  samples  of  soil  were  taken 
June  27.  In  this  case  the  rows  were  planted  3  feet  apart,  and 
the  table  given  on  page  161  shows  a  difference  of  4.5  per 
cent  in  the  upper  six  inches  on  the  sunny  and  shaded  sides  of 
the  row. 

Then,  too,  if  the  roots  of  the  crop  do  not  penetrate  deeply 
into  the  soil,  more  water  will  be  required,  for  the  d,°uble  reason 
that  more  water  is  liable  to  be  lost  by  percolation  below  the  root 
zone,  and  because  a  greater  frequency  of  water  will  be  required 
than  if  the  roots  went  deeper  ;  hence,  there  will  be  more  loss  by 
surface  evaporation. 

2.  The  character  of  the  soil. — In  the  studies  which  have  been 
made  regarding  the  amount  of  water  required  for  a  pound  of  dry 
matter,  there  has  been  nothing  to  indicate  that  a  plant  growing 
in  one  soil  requires  more  water  than  when  growing  in  another, 
provided  there  is  always  an  abundance  of  plant -food  available  to 
the  crop  throughout  its  period  of  growth.  In  other  words,  if  it 
were  possible  to  avoid  losses  by  seepage,  and  by  evaporation 
other  than  that  which  takes  place  through  the  growing  crop,  it 
does  not  appear  that  the  duty  of  water  would  vary  with  the 
character  of  the  soil. 

.  But,  while  it  is  true  that  by  skillful  management  water  mny 
be  distributed,  even  over  the  soils  of  coarse  texture,  with 
little  or  no  waste  through  seepage,  and  while  surface  evaporation 
may  be  very  greatly  reduced  by  suitable  methods  of  applying  the 
water  and  of  tillage,  there  will  always  be  those  living  under  the 
same  water  supply  who  are  less  skillful  than  others,  and  who  will, 
by  their  lack  of  skill,  require  more  water  in  order  to  secure  the 
same  yields  ;  and,  in  consequence  of  this,  the  duty  of  water  will 
vary  to  some  extent  with  the  soil. 

There  are  really  wide  variations  in  the  effectiveness  of 
mulches  developed  from  different  soils,  and  while  these  are  not 
as  great  as  the  variations  in  the  rates  of  seepage,  the  losses  of 
water  through  surface  evaporation  are  less  completely  under  con- 
trol than  those  due  to  percolation.  The  force  of  these  statements 


Conditions  Modifying  T>uty  of    Water          201 

will    be    more    readily  appreciated   after    a    study  of    the  results 
given  in  the  following  table: 

* Table  showing  the  difference  between  the  effectiveness  of  mulches  developed  from 
different  kinds  of  soil 


Black  marsh  soil 

Tons  per  acre 

Inches  of  water 
Per  cent  saved  by  mulches 
Sandy  loam : 

Tons  per  acre 

Inches  of  water 

Per  cent  saved  by  mulches 

Virgin  clay  loam : 

Tons  per  acre 2,414 

Inches  of  water 21.31 

Per  cent  saved  by  mulches 


-  —  Loss  of  water  per  100  days  —  - 
Mulch          Mulch          Mulch 
1:          No  mulch    1-in.  deep    2-in.  deep    3-in.  deep 

Mulch 
4-in.  deep 

588 
5.193 

355 
3.1'J 
39.54 

270 
2.384 
54.08 

256.4 
2.265 
56.39 

252.5 
2.23 
57.06 

ulches 

741.5 
6.548 


373.7 
3.3 
49.6 


11.13 
4776 


339.3 
2.996 
54.24 

979.7 
8.652 
59.38 


287.5  315.4 

2.539  2.785 

61.22  57.47 

889.2  883.9 

7.852  7  805 

63.13  63.34 


The  results  in  this  table  were  secured  by  filling  cylinders  of 
galvanized  iron,  having  a  depth  of  22  inches  and  a  cross-section 
of  yo  of  a  square  foot,  with  the  soil  named,  by  thorough  tamp- 
ing, and  then  removing  a  depth  of  these  soils  equal  to  1,  2,  3 
and  4  inches,  returning  enough  of  each  kind  in  a  loose,  crumbled 
condition  to  fill  the  cylinders  again  level  full,  thus  forming 
mulches  of  the  respective  depths.  Under  these  conditions,  the 
soils  were  exposed  in  the  open  field  during  42  days  to  the  normal 
atmospheric  conditions,  except  that  during  times  of  rain  the 
cylinders  were  covered.  Water  was  added  every  10  days  to  the 
reservoirs  shown  in  Fig.  36,  bringing  the  lowered  surface  back 
to  a  standard  level. 

It  will  be  seen  that  while  the  black  marsh  soil  lost  water 
through  the  unmulched  surface  at  the  rate  of  5.88  tons  per  acre 
per  day,  the  sandy  loam  lost  water  at  the  rate  of  7.42  tons, 
and  the  virgin  clay  loam  at  the  rate  of  24.14  tons  per  acre  per 
day,  the  latter  exceeding  the  two  former  more  than  three-  and 
four-fold.  And,  then,  when  the  losses  through  mulches  of  cor- 
responding depths  are  compared,  it  will  be  seen  that  although 


*Fifteenth  Ann.  Kept.  Wis.  Agr.  Expt.  Station,  page  137. 


202 


Irrigation   and    Drainage 


these  are  much  less  than  through  the  undisturbed  soil,  yet  the 
relative  differences  are  nearly  as  large.  That  is  to  say,  the  soil 
which,  in  the  firm  condition,  has  brought  the  largest  amount  of 
water  to  the  surface,  has  also,  when  its  surface  1,  2,  3  or  4 


_^ 

~=^ 

Ci 

=£= 

\l 

m 

\t 

=-^= 

\t 

$% 

IF 

^= 

\i 

w 

li 

-• 

\i 

,,, 

If 

§ 

\                  .  .                  \ 

Fig.  36.    Method  of  measuring  effectiveness  of  mulches. 

inches  were  converted  into  a  mulch,  permitted  the  largest  losses 
to  take  place  ;  while  the  soil  having  the  slowest  rate  of  loss 
when  the  surface  was  firm  has  also  given  the  least  evaporation 
through  the  several  depths  of  mulches. 

If  the  losses  per  100  days,  expressed  in  inches,  are  brought 
into  contrast,  they  stand  as  shown  below: 


No  mulch 

INCHES 

Virgin  clay  loam 21,31 

Black  marsh  soil. . .  5.19 


Difference 1612 


1-inch 
mulch 

INCHES 
11.13 
3.12 

8.01 


2-inch 
mulch 

INCHES 
8.65 
2.38 

6.27 


3-inch 
mulch 

INCHES 

7.85 
2.27 

5.58 


4-inch 
mulch 

INCHES 
7.81 
2.23 

5.58 


Jt  will   be  seen  from  this   table   that  very  wide    differences 
exist  between  the   losses  of   moisture  through   mulches   of   like 


Conditions   Modifying   Duty  of   Water         203 

depth,  when  developed  from  soils  of  different  textures,  and  it  is 
plain  that  with  equal  losses  by  percolation  from  the  three  soils 
here  under  consideration,  more  water  would  be  required  to  bring 
a  crop  to  maturity  on  the  virgin  clay  loam  than  on  either  of  the 
other  soils,  and  hence,  that  the  duty 'of  water  would  be  less, 
supposing,  of  course,  that  the  three  soils  were  equally  fertile. 

Where  water  is  plentiful  and  is  being  used  freely,  and  es- 
pecially where  irrigation  by  flooding  is  being  practiced,  the  soils 
having  the  coarsest,  most  open  texture  will  waste  the  most  water 
by  percolation  through  the  zone  of  root  feeding.  Hence  on  this 
account  the  duty  of  water  would  be  smaller  on  these  soils  than 
on  those  having  finer  texture.  But,  on  the  other  hand,  the  sur- 
face evaporation  from  the  closer  soils  is  so  much  greater  than 
from  the  sandy  soils  that  the  duty  of  water  i£  much  more  nearly 
equal  on  them  than  it  could  be  were  it  not  for  these  opposite 
characteristics. 

Bearing  upon  this  point  E.  Perels,*  citing  Eduard  Markus, 
gives  the  results  of  observations  covering  three  years  in  northern 
Italy  on  different  kinds  of  soils  and  with  different  crops,  from 
which  it  appears  that  rice,  meadows  and  field  crops  use  water  in 
the  ratio  of  7  to  3  to  1,  respectively,  and  when  field  crops  are 
grown  upon  very  heavy  soil,  heavy  soil,  medium  soil,  or  light 
soil,  they  take  water  in  the  ratio  of — 

Very  heavy  soil        Heavy  soil        Medium  soil        Light  soil 
100  .    .  to  .    .  115  .    .  to  .    .  168  .    .  to  .    .  230 

It  is  quite  probable,  however,  that  these  ratios  represent  the 
relations  of  the  degree  of  permeability  of  these  soils  under  the 
conditions  of  the  district,  rather  than  the  necessary  amounts  of 
water  required  for  irrigation  on  these  soils,  where  simply  the 
transpiration  from  the  crops  and  the  evaporation  from  the  soils 
is  considered.  In  the  cases  of  the  rice  and  meadows,  it  is  cer- 
tain that  large  percolation  or  surface  drainage  must  have  occurred. 

The  losses  of  water  by  seepage  from  canals  and   reservoirs 


*Landwirthschaftlicher  Wasserbau,  p.  501. 


204  Irrigation   and    Drainage 

and  the  various  distributaries  will,  of  course,  be  relatively  greater 
in  regions  of  soils  of  coarse  texture  than  where  the  soils  are  finer, 
so  that  here  is  a  factor  modifying  the  duty  of  water  as  con- 
sidered from  the  standpoint  of  the  water  company  and  irrigation 
engineer  especially,  but  also  with  the  large  irrigator,  who  has 
extensive  distributaries,  through  which  the  water  must  be  con- 
veyed before  it  is  finally  taken  out  upon  the  land.  It  should  be 
emphasized  that  our  discussion  has  reference  to  the  duty  of  water 
after  it  has  reached  the  field  where  it  is  used. 

If  it  shall  be  found  true  that  the  continued  growth  of  large 
crops  upon  a  piece  of  land,  and  the  consequent  more  complete 
evaporation  of  all  water  brought  to  the  soil,  thus  curtailing  the 
drainage,  tends  to  develop  alkalies  to  an  injurious  extent,  or 
other  prejudicial  salts,  so  that  flooding  or  leaching  by  irrigation 
shall  be  found  necessary  in  order  to  restore  fertility,  then  here, 
again,  the  character  of  the  soil  will  modify  the  amount  of  water 
required. 

3.  The  character  of  the  rainfall  will  necessarily  modify  in  a 
marked  manner  the  amount  of  additional  water  which  may  be 
used  to  advantage  in  the  production  of  crops.  It  has  already 
been  pointed  out  on  page  103  that  the  difference  in  the  character 
of  the  rainfall  in  parts  of  California,  Oregon  and  Washington,  as 
compared  with  that  of  western  Kansas  and  Nebraska,  may  explain 
why  equivalent  amounts  of  rain  are  much  more  effective  in  the 
former  than  in  the  latter  regions,  and  if  it  is  true  that  the  fre- 
quent summer  rains  east  of  the  Eocky  Mountains  do  tend  to  hold 
the  development  of  the  roots  of  crops  closer  to  the  surface,  and 
also  to  destroy  the  effectiveness  of  soil  mulches,  it  is  clear  that 
the  duty  of  water  in  climates  where  most  of  the  growing  season 
is  an  uninterrupted  rainless  period  will  be  relatively  higher  than 
where  frequent  but  inefficient  showers  tend  to  reduce  the  effi- 
ciency of  mulches,  and  to  hold  the  roots  of  crops  closer  to  the 
surface.  It  is,  therefore,  likely  to  be  found  true  that  more  water 
will  be  required  for  like  results  in  western  Texas,  Oklahoma, 
Kansas,  Nebraska,  and  the  Dakotas,  and  similar  climates,  than 
will  be  required  where  the  whole  summer  season  is  one  con- 
tinuous interval  of  no  rain. 


Conditions   Modifying   Duty   of   Water         205 

In  still  more  humid  climates,  but  where  there  are  frequent 
recurrences  of  intervals  of  drought,  the  amount  of  water  wnich 
must  be  used  in  order  to  secure  full  yields  will  be  relatively 
larger  than  would  be  required  in  rainless  countries,  because  the 
surface  losses  of  moisture  will  be  relatively  greater,  as  well  as 
those  from  percolation  and  drainage. 

4.  The  character  of  the  subsoil,  as  well  as  that  of  the  surface 
soil,   is    an    important   factor  in  determining  the  duty  of  water, 
especially    in    the    hands    of    the    unskillful    irrigator,    and    par- 
ticularly  so    if    he    possesses    no    knowledge,    or    exercises    poor 
judgment,   regarding    the   water-holding    power    of    the    soil    to 
which   the  water  is    being    applied.     Where    the    texture    of    the 
subsoil  is  coarse  and  its  water -holding  power  small,  it  requires 
the   best  of  judgment,  both  in   regard    to   the    amount  of  water 
which  may  be  applied  at  one  time  and  as  to  the  rate  at  which  it 
should   be    led  over  the  surface  or  along  the  furrows,  in  order 
that  there  shall  be  no  waste  by  percolation  below  the  depth  of 
root  feeding. 

It  has  been  pointed  out  that  even  moderately  fine  sands  8 
feet  above  the  ground  water  quickly  lose  by  percolation  all  but  4 
per  cent,  or  less,  of  their  dry  weight,  of  the  water  given  to  them. 
Since  plants  will  suffer  for  water  when  such  soils  have  lost  all 
but  2  to  3  per  cent  of  their  dry  weight  of  the  soil  moisture,  it 
follows  that  in  4  feet  in  depth  of  such  a  subsoil  there  is  room  for 
only  1.5  to  2  per  cent  of  water,  or  1  to  1.5  inches,  to  be  applied 
at  one  time,  without  loss  taking  place  by  percolation  below  the 
depth  of  root  action.  It  is  plain,  therefore,  that  on  open  soils 
the  duty  of  water  will  be  relatively  small,  unless  great  skill  and 
rare  judgment  are  exercised  in  its  application. 

5.  The  frequency  and   thoroughness  of  cultivation  after  irriga- 
tion is  another  factor  which  will  modify  the  duty  of  water.     For 
the  effectiveness  of  soil  mulches  is  modified  as  well  by  the  fre- 
quency of  stirring  as  by  its  depth.     The  force  of  this  statement 
will   be    better  appreciated  when  the  results  given  in  the  table 
which  follows  have  been  considered: 


206 


Irrigation   and    Drainage 


Table  showing  the  loss  of  water  from  a  virgin  clay  loam  through  mulches  1,  $, 
and  3  inches  deep,  when  cultivated  once  in  two  weeks,  once  per  week,  and 
twice  per  week 

Not         Once  in    Once  per    Twice  per 
cultivated    2  weeks       week  week 

Cultivated  1  inch  deep—  PER  ACRE  PE«  ACRE  PER  ACRE  PER  ACRE 

The  loss  in  tons  per  100  days  was 724.1  551.2  545  527.8 

The  loss  in  inches  per  100  days  was..       6.394  4.867  4.812  4.662 

The  percentage  of  water  saved  was..  23.88  24.73  27.1 

Cultivated  2  inches  deep— 

The  loss  in  tons  per  100  days  was 724.1 

The  loss  in  inches  per  100  days  was . .        6.394 


The  percentage  of  water  saved  was.  . 
Cultivated  3  inches  deep— 

The  loss  in  tons  per  100  days  was  ____ 
The  loss  in  inches  per  100  days  was  .  . 
The  percentage  of  water  saved  was  .  . 


609.2 
5.38 
15.88 


552.1 
4.875 


515.4 
4.552 

28.81 


724.1 
6.394 


612 

5.28 
15.49 


531.5 


26.6 


495 
4.371 
31.64 


It  will  be  seen  from  this  table  that  with  each  of  the  three 
depths  of  cultivation  the  loss  of  water  decreased  with  the  fre- 
quency, so  that  the  per  cent  of  moisture  saved  by  the  cultivation, 
when  computed  on  that  which  was  lost  with  no  cultivation,  was 
more  than  31  for  3  inches  deep  twice  per  week,  as  against  a  sav- 
ing of  only  15  per  cent  where  the  same  cultivation  was  made  only 
once  in  two  weeKs.  That  is  to  say,  if  one  is  cultivating  ground 
of  this  character  3  inches  deep  twice  per  week,  the  saving  over 
no  cultivation  may  be  at  the  rate  of  2.29  tons  per  acre  per  day, 
or  22.9  tons  per  each  10  days,  or  2  acre-inches  per  100  days. 

The  results  presented  in  the  table  were  obtained  in  our 
plant-house,  with  cylinders  52  inches  deep  and  18  inches  in 
diameter,  filled  with  soil  under  a  nearly  still  air  and  a  compara- 
tively low  mean  temperature,  not  exceeding  55°  F.,  during  the 
short  days  and  long  nights  of  December  and  January,  so  that 
the  observed  losses  in  the  several  cases  must  be  looked  upon  as 
small,  and  below  what  may  obtain  under  field  conditions.  It  is 
plain,  therefore,  that  in  orchard  irrigation  and  in  arid  climates, 
under  a  clear  sky,  dry  air  and  high  temperature,  the  duty  of 
water  during  the  long  seasons  may  be  very  materially  increased 
by  adequate  cultivation,  and  decreased  by  the  lack  of  it. 

The  same  will  also   be  true,  tyit  in  a   less  marked  degree, 


Conditions   Modifying   Duty   of   Water         207 

with  all  cultivated  crops  where  the  soil  is  not  completely  shaded 
by  the  plants  on  the  ground. 

6.  The  closeness  of  planting  is  another  factor  which  affects 
the  duty  of  water  when  this  is  expressed  in  terms  of  land  served, 
rather  than  in  terms  of  crop  produced.     This  is  particularly  true 
in  climates  where  a  rainy  season  contributes  a  considerable  por- 
tion of  the  moisture  needed  to  produce  a  crop  ;  because  if  one  is 
contented  with  a  small  yield  per  acre,  a  comparatively  thin  stand 
upon  the  ground,  with  thorough  tillage,  may  often  be  brought  to 
full   maturity  with   a    relatively  small  amount    of  water   applied 
by  irrigation,  thus  making  the  duty  of  water  to  appear  very  high, 
whereas  if  the  plants  were  made  to  stand  as  closely  as  the  sun- 
shine would    permit,   much    more  water,  when  expressed  simply 
in  acre -inches,  would  be  required.     The  real  duty,  however,  might 
be  even  higher  in  the  second  case,  when  expressed  in  terms  of 
yield  per  acre. 

7.  The   fertility    of  the    land   is    still    another    factor  which 
affects    the  duty  of  water,  tending  to  make    it   appear   less  the 
richer  and  more  fertile  the  soil  is,  when  the  standard  of  com- 
parison is  the  unit  area  rather  than  the    yield   of   crop.      This 
apparent  decrease  in  the  duty  results  from  the  larger  evaporation 
of  water  which  takes   place    from   the  more  vigorous  growth    of 
vegetation,   and   the    closer   stand  which    the    larger   amount   of 
available  plant -food    renders   possible.     In    such  cases  as  these, 
however,  the  real  duty  of  water  is  higher  on  the  most  fertile  soil, 
when  this  is  based  upon  the  actual  yields  per  acre  ;  not  so  much 
because  the  plant  uses  the  water  more  economically,  as  that  the 
necessary  loss  from  the  soil  itself  is  relatively  less  with  the  large 
yield  than  it  is  with  the  small  yield  per  acre.     The  loss  from  the 
soil  direct  may  even  be  actually  larger  with  the  smaller  crop  on 
the  ground,  on  account  of  a  less  complete  shading  and  stronger 
air  movement  close  to  the  surface. 

8.  The  frequency  of  applying  water  also  modifies  the  quantity 
which  will   be    used    during  a  season.     This    may  be   true  even 
when  the  greatest  skill  is  exercised  in  the  application  of  the  water. 
In  the  first   place,   too   frequent   application    of  water   in   small 
quantities  at  a  time  not  only  increases  in  a  marked  degree  the 


208  Irrigation   and    Drainage 

direct  loss  of  moisture  from  the  wet,  unmulehed  soil  ;  but  it  may 
have  a  tendency,  as  has  been  pointed  out,  to  induce  a  superficial 
development  of  roots,  causing  the  crop  to  show  signs  of  need  of 
water  sooner  than  would  be  the  case  if  a  smaller  number  of  more 
thorough  irrigations  were  resorted  to.  This  is  so,  not  only  be- 
cause the  water  disappears  sooner  from  the  soil,  but  also  because 
of  the  larger  amount  of  root-pruning  which  results  from  culti- 
vation where  the  roots  are  developed  near  the  surface  of  the 
ground. 

It  is  probable  that  a  large  supply  of  water  in  the  soil  during 
the  early  stages  of  growth  of  many  plants  tends  to  develop  in 
them  a  possibility  for  using  more  water.  In  some,  at  least,  of 
our  experiments  with  corn,  oats,  potatoes  and  clover,  where  we 
have  started  with  like  amounts  of  water  in  the  soil,  and  have 
watered  one  set  of  plants  every  seven  days  while  the  others 
were  allowed  to  go  without  water  until  the  soil  was  so  far  ex- 
hausted that  the  plants  were  plainly  suffering  for  want  of  mois- 
ture, it  was  found  that  these  plants  not  only  did  not  use  water  as 
rapidly  after  they  were  given  it  as  did  those  which  had  been 
watered  every  week,  but  they  used  the  water  they  did  have  with 
relatively  greater  economy.  Whether  this  was  because  the  plants 
were  smaller,  and  thus  presented  a  smaller  surface  to  the  air  and 
sun,  or  whether  the  size  or  number  of  breathing  pores  per  unit 
area  of  foliage  was  actually  less,  cannot  yet  be  stated  ;  but  it 
appeared  evident  that  for  some  reason  the  plants  which  had  not 
been  watered  at  first  were  later  not  able  to  use  the  larger  amount 
of  water  which  was  given  to  them,  as  they  might  have  done  had 
they  been  more  freely  watered  at  first. 

THE    AMOUNT     OF    WATER    USED    IN     IRRIGATION 

It  is  very  difficult,  indeed,  to  get  data  bearing 
upon  this  important  subject  which  may  be  regarded  as 
in  every  way  satisfactory  and  trustworthy.  Nearly  all 
statistics  are  necessarily  so  general  in  their  character, 
the  exact  amount  of  land  to  which  the  water  of  a 


Amount  of   Water    Used  in  Irrigation         209 

stated  canal  is  actually  applied  is  so  uncertain,  ami 
the  amount  of  water  lost  by  seepage  and  evaporation 
from  the  canal  and  its  distributaries  before  the  land  to 
which  it  is  nominally  applied  is  reached,  is  so  variable 
and  indeterminate  that  the  best  which  can  be  said 
regarding  most  available  data  is  that  they  should  be 
looked  upon  as  only  rough  approximations.  Further 
than  this,  it  must  be  constantly  borne  in  mind,  when 
dealing  with  the  problem  of  how  much  water  is  re- 
quired,for  irrigation,  with  all  the  variations  of  weather, 
climate,'  crops,  soils  and  degrees  of  skill  in  applying 
water  which  exist,  that  were  sufficiently  exact  data  at 
hand  covering  a  wide  range  of  conditions,  it  would 
still  be  impossible  to  combine  them  into  averages  not 
requiring  wide  marginal  allowances  to  be  made  when 
specific  application  is  desired.  But,  notwithstanding 
all  this,  general  statements  may  be  helpful  if  only 
they  are  rightly  considered. 

Referring,  first,  to  Italy,*  where  irrigation  has  long 
been  systematically  practiced,  it  is  generally  calculated 
that  in  Piedmont  one  cubic  foot  of  water  per  second 
will  serve  satisfactorily  55  acres  of  land ;  but  on  ac- 
count of  loss  by  evaporation  and  seepage,  this  is 
reduced  to  51.4  acres,  this  providing  sufficient  for 
4.63  inches  of  water  every  10  days  during  the  irri- 
gation season. 

Under  the  canal  of  Ivrea,  where  a  large  amount 
of  rice  is  grown,  which  is  given  more  water  than  ordi- 
nary crops,  one  second -foot  serves  but  42.75  acres,  or 
at  the  rate  of  5.668  inches  every  10  days ;  and  under 

*3aird  Smith,  Italian  Irrigation,  Vol.  I. 

N 


210  Irrigation   and    Drainage 

the  Gattinara  canal,  water  is  provided  which  may  be 
applied  at  the  rate  of  5.289  inches  per  10  days.  But 
under  the  Busca  canal,  where  the  utmost  economy  is 
practiced  and  every  drop  is  saved,  the  duty  of  water 
is  so  much  increased  that  one  second -foot  serves  106 
acres,  making  a  depth  of  water  equal  to  2.245  inches 
every  10  days  for  the  irrigation  season. 

Bringing  all  cases  cited  by  Smith  into  one  table, 
and  expressing  the  second -foot  in  inches  of  water  per 
10  days,  the  following  results  are  found : 

Amount  of  water  used  for  irrigation  in  Italy 


No.  of  acres 
per  sec.  foot 

No-  of  inches  of  water 
per  10  days 

No.  of  acres 
per  sec.  foot 

No.  of  inches  of  water 
per  10  days 

51.4 

4.63 

99.3 

2.397 

45 

5.289 

80.4 

2.96 

106 

2.245 

66.62 

3.572 

100.6 

2.366 

61.8 

3.851 

63 

3.778 

66.6 

3.574 

90.6 

2.627 

69.2 

3.44 

50.3 

4.732 

63.9 

2.837 

70 

3.4 

67.2 

3.542 

77 

3.091 

90.4 

2.633 

69 

3.449 

This  gives  a  general  average  for  ordinary  crops  of 
3.39  inches  of  water  every  10  days  and  33.9  inches 
per  100  days,  were  it  used  at  such  a  rate  for  so  long 
a  period. 

In  the  rice  irrigation  of  Italy,  the  amount  of  water 
provided  is  said  to  be  at  the  rate  of  5.568  inches, 
5.921,  3.412,  9.521,  and  3.334  inches  every  10  days 
in  as  many  districts,  or  an  average  of  5.55  inches  per 
10  days. 


Amount   of    Water    Used    in   Irrigation         211 

In  Spain,  where  the  rainfall  is  less  than  in  Italy, 
and  where  greater  economy  of  water  is  practiced,  19 
important  allotments*  of  water  give  an  average  ot 
2.353  inches  every  10  days  for  various  sections  ot 
that  country. 

In  France,  in  the  Department  of  the  Upper 
Garonne,  contracts  were  made  calling  for  water  at 
the  rate  of  three -fourths  of  a  liter  per  hectare  per 
second,  which  makes  a  duty  of  about  93.25  acres  per 
second  foot,  or  water  applied  at  the  rate  of  2.552 
inches  every  10  days.  In  the  department  of  Vau- 
cluse,  the  concession  was  at  the  rate  of  only  1.361 
inches  per  10  days. 

In  Egypt,  Willcockst  states  that  in  winter  water 
is  applied  at  an  average  depth  of  10  c.  in.,  equal  to 
3.937  inches,  once  in  40  days,  which  is  a  rate  of 
.984  inches  once  in  10  days;  but  in  summer  the  first 
watering  is  at  the  rate  of  11.5  c.  m.,  equal  to  4.528 
inches,  while  subsequent  waterings  are  at  the  rate  of 
3.412  inches  in  depth.  Cotton  requires  this  amount 
once  in  20  days,  or  at  the  rate  of  1.706  inches  per  10 
days.  Rice  is  given  water  at  the  rate  of  3.412  inches 
once  every  10  days,  and  maize  gets  the  same  amount 
every  15  days,  or  at  the  rate  of  2.276  inches  in  depth 
every  10  days. 

Wilsont  gives  a  table  of  general  averages  of  the 
duty  of  water  in  different  parts  of  the  world,  which 
we  put  in  the  form  stated  below: 


*Hall,  Irrigation  Development,  p.  523. 
tWillcocks,  Egyptain  Irrigation,  pp.  234,  235. 
^Manual  of  Irrigation  Engineering,  Sec.  Ed. ,  p.  49. 


212 


Irrigation   and    Drainage 


Amount  of  neater  used  in  irrigation  in  different  countries 
Name  of  country  No.  of  acres  per  sec.-ft.  No.  of  inches  per  10  days 


Northern    India  .    . 

Italy 

Colorado 

Utah 

Montana 

Wyoming  ....... 

Idaho  

New  Mexico  .... 
Southern  Arizona  . 
San  Joaquin  Valley 
Southern  California 


60  to  150 

65  to     70 

80  to  120 

60  to  120 

80  to  100 

70  to     90 

60  to     80 

60  to     80 

100  to  150 

100  to  150 

150  to  300 


3.967  to  1.587 
3.661  to  3.4 
2.975  to  1.983 
3.967  to  1.983 
2.975  to  2.38 
3.4  to  2.644 
3.967  to  2.975 
3.967  to  2.975 
2.38  to  1.587 
2.38  to  1.587 
1.587  to  .793 


E.   Perels*   tabulates  the  duty  of  water  in  Algeria 


as  follows 


Water  required  for  irrigation  in  Algeria 


No.  of 

Each            During  the 

Length  of 

Crops 

waterings 

application 

season 

culture  period 

INCHES  IN 

INCHES  IN 

MONTHS 

DEPTH 

DEPTH 

Alfalfa  .    .    . 

.       10 

1.575 

15,75 

6 

Vegetables    . 

.       36 

1.575 

56.7 

6 

Cotton  .    .    . 

J 

Flax  .... 

10 

2.52 

25.2 

5 

Sesame  .   .    . 

) 

Maize  .... 

4 

1.575 

6.3 

2 

Winter  grain 

3 

3.937 

11.87 

7 

Oranges  .  .    . 

.      12 

1.575 

18.9 

6 

Tobacco.   .    . 

4 

1.575 

6.3 

3 

Grapes  .    .    . 

4 

4.725 

18.9 

3 

From  another  general  table  giving  the  duty  of 
water  in  different  countries,  by  Flynn,t  the  results 
which  follow  are  derived: 


*Landwirthschaftlicher  Wasserbau,  zweite  Auflage,  p.  502. 
t  irrigation  Canals  and  Hydraulic  Engineering,  p.  293. 


Amount   of   Water    Used   in   Irrigation         213 


Amount  of  water  used  in  irrigation  in  different  countries 


Name  of         No. 

of  acres 

No.  of  inches 

Locality 

country         per 

sec.  -foot 

per  10  days 

Eastern  Jumna  Canal  .    . 

India 

306 

.778 

Western  Jumna  Canal    .... 

<  < 

240 

.989 

Ganges  Canal  

" 

232 

1.026 

Canals  of  Upper  India  

<  t 

267 

.891 

Canals  of  India  —  average  .    .    . 

t  < 

250 

.952 

Bari  Doab  Canals  . 

<  t 

155 

1.536 

Madras  Canals  (rice)    

<  < 

66 

3.606 

Tanjore  (rice)    

(  < 

40 

5.964 

Swat  Eiver  Canal,  1888-89  .    .    . 

t  < 

216 

1.345 

Swat  River  Canal,  1889-90  .    .    . 

<  i 

177 

1.202 

Western  Jumna  Canal,  1888-89  . 

4  t 

143 

1.664 

Western  Jumna  Canal,  1889-90  . 

I  I 

179 

1.33 

Bari  Doab  Canal,  1888-89  .    .    . 

I  I 

201 

1.184 

Bari  Doab  Canal,  1889-90  .    .    . 

« 

227 

1.049 

Sirhind  Canal,  1888-89    .       .   . 

<  ( 

180 

1.322 

Sirhind  Canal,  1889-90    .... 

I  ( 

180 

1.322 

Chenab  Canal,  1888-89    .    .    .   . 

(  I 

154 

1.545 

Chenab  Canal,  1889-90  

" 

154 

1.545 

Nira  Canal  

<  ( 

186 

1.28 

Genii  Canal  . 

Spain 

240 

.992 

Jucar  (rice)  

<  < 

35 

6.8 

Henares  Canal  

11 

157 

1.516 

Canals  of  Valencia  

1  1 

242 

.984 

Forez  Canal  

France 

140 

1.7 

Canals  south  of  France  .... 

« 

70 

3.4 

Sefi  Canals,  Southern  France  . 

4  1 

60 

3.877 

Sen,  or  Lower  Nile  Canals   .    . 

Egypt 

350 

.68 

Sen,  or  Lower  Nile  Canals   .    . 

«  < 

274 

.867 

Canals  of  Northern  Peru  .... 

Peru 

160 

1.488 

Canals  of  Northern  Chili  .... 

Chili 

190 

1.253 

Canals,  Lombardy  . 

Italy 

90 

2.644 

Canals,  Piedmont  

<  < 

60 

3.877 

Marcite  

1 

to  18 

238  to  13.22 

Sefi  Canals*  Victoria  .    ...    .    . 

Australia 

200 

1.19 

214  Irrigation   and    Drainage 

Amount  of  water  used  in  irrigation— continued 

Name  of        No.  of  acres     No.  of  inches 
Locality  country          per  sec.  foot       per  10  days 

Sweetwater,  San  Diego  ....  California  500  .476 

Pomona,  San   Bernardino  .    .    .  500  .476 

Ontario "  500  .476 

California "  80tol50    2.975tol.587 

Canals  of  Utah  Territory    .    .    .  Utah  100  2.38 

Canals  of  Colorado Colorado  100  2.38 

Canals  of  Cache  la  Poudre  ...  193  1.233 

Canals  of  Colorado 55  4.328 

It  is  apparent,  from  the  data  which  have  been 
presented,  that  the  amount  of  water  actually  used  in 
irrigation  in  different  countries  and  for  different  crops 
is  an  extremely  variable  quantity;  so  much  so,  indeed, 
that  it  is  hardly  possible  to  deduce  from  available  sta- 
tistics a  mean  value  for  the  duty  of  water.  But,  using 
the  100  cases  at  hand  from  all  parts  of  the  world,  and 
excluding  those  which  apply  to  rice  culture  and  the 
irrigation  of  water-meadows  and  sugar  cane,  it  ap- 
pears that  a  cubic  foot  of  water  per  second  is  made 
to  serve  on  the  average  117.6  acres.  If  this  water 
were  applied  to  the  land  once  in  10  days,  it  would 
cover  the  surface  to  a  depth  of  2.024  inches  each 
watering,  and  during  a  season  of  100  days  would  be 
the  equivalent  of  20.24  inches  of  rain. 

Sugar  cane  is  a  crop  which  demands  large  and  fre- 
quent irrigations  in  order  to  secure  the  largest  returns 
from  the  soil.  In  the  Sandwich  Islands  one  cubic 
foot  of  water  per  second  is  required  for  41.6  acres  of 
cane,  and  it  is  found  that  if  the  duty  is  made  larger 
than  60  acres  per  second -foot,  a  falling  off  in  yield  is 


Highest  Probable   Duty  of  Water 


215 


sure  to  result.  In  India  and  Siam  writers  on  this  sub- 
ject state  that  from  43  to  45  acres  is  the  usual  duty 
of  a  second-foot.  The  mean  value  for  good,  thorough 
watering  appears  to  be  43.2  acres  per  second -foot,  or 
a  depth  of  water  aggregating,  for  the  year,  between  19 
and  20  feet  on  the  level. 

If  reference  is  again  made  to  the  table  on  page 
198,  it  will  be  seen  that  this  duty  of  water  is  much 
smaller  than  was  realized  in  the  experiments  cited. 
According  to  the  results  there  given,  one  second -foot 
should  be  able  to  serve  the  number  of  acres  stated  in 
the  table  below: 


The  highest  probable  duty  of  water  tor  different  crops  expressed  in  acres  per 
second-foot  for  different  yields  per  acre 


Yield  per 
acre 

15  bushels 

20       " 

30       " 

40       " 

50       " 

60       " 

70       " 

80       " 

90  " 
100  " 
200  " 
300  " 
400  " 

1  tou 

2  tons 

3  " 

4  " 


Wheat         Barley         Oats 


Maize       Potatoes    Clover  hay 


ACRES 

529.2 
352.8 
264  6 

ACRES 

593.0 
395.3 
296  5 

ACRES 
1002 

751.5 
501  0 

ACRES 

1039 
779.2 
519  5 

ACRES 

ACRES 

176.4 
141  1 

197.6 
158  1 

375.7 
300  6 

389.6 
311.7 

117.6 

131.7 
112  9 

250.5 
214.3 

259.7 
222.6 

2493.7 
2137.4 

98.8 

187.9 

194.8 

1870.2 



167.0 
150.3 

173.2 
155.8 

1662.4 
1496.2 
748.1 

498.7 

374  0 

322  7 

161.3 

107.6 

80.7 

216  Irrigation   and    Drainage 

In  constructing  this  table,  the  season  of  growth 
has  been  taken  at  100  days  for  wheat  and  oats,  80 
days  for  barley,  110  days  for  maize,  130  days  for  pota- 
toes, and  60  days  for  one  crop  of  clover  hay.  It  has 
further  been  assumed  that  the  ground  at  seeding  time 
is  well  supplied  with  moisture,  while  at  harvest  it  is 
only  so  much  dried  out  as  to  have  just  become  ready 
for  another  watering. 

As  in  the  experiments  which  gave  the  fundamental 
data  for  the  table  above,  the  soil  was  more  closely 
planted  than  is  practicable  under  field  conditions,  the 
loss  of  water  by  evaporation  from  the  soil  of  the  field 
is  likely  to  be  greater,  relatively,  than  was  the  case  in 
the  experiments  ;  hence,  the  observed  duty  of  water  is 
likely  to  be  lower  than  the  table  indicates.  Again, 
in  the  case  of  the  smaller  yields  per  acre,  the  evapo- 
ration from  the  soil  will  necessarily  be  relatively  larger 
than  where  the  heavier  crops  are  produced  ;  hence,  the 
duty  expressed  for  water  when  the  yields  are  small  is 
likely  to  be  farther  from  the  possibilities  than  in  the 
cases  where  the  jdelds  per  acre  are  larger. 

If  the  amount  of  water  which  the  last  table  indi- 
cates is  required  to  produce  a  crop  of  the  various 
kinds  is  expressed  in  cubic  feet,  the  figures  will 
stand  : 

8,640,000  cu.  ft.  of  water  may  produce  7,056  bushels  of  wheat 
8,640,000   "     "    "       "        "          "       15,030         "        "  oats 
6,912,000   "     "    "      "        "          "         7,906         "       "  barley 
9,5040,000   "     "    "      "        "          "        15,580         "       "  maize 
11,232,0000   "     "    "      "        "          "      149,620         "       "  potatoes 
5,184,000    "     "    "       "        "          "         322.7  tons  of  hay, 


Duty  of  Water  in  Rice    Culture  217 

where  the  number  of  cubic  feet  is  the  product  of  one 
second -foot  into  the  number  of  seconds  in  the  season 
of  growth,  and  the  number  of  bushels  is  the  product 
of  the  yield  per  acre  into  the  number  of  acres  irri- 
gated. 

THE    DUTY    OF    WATER    IN    RICE    CULTURE 

The  aquatic  nature  of  the  rice  plant  makes  the 
demands  for  water  quite  different  from  those  of  ordi- 
nary agricultural  crops,  and  so  different  are  these 
needs  that  the  quantity  of  water  required  to  bring  a 
crop  to  maturity  is  determined  by  quite  different 
factors.  The  duty  of  water,  therefore,  in  rice  culture 
could  not  consistently  be  considered  in  connection  with 
that  of  ordinary  crops. 

The  normal  habitat  of  this  plant  is  low,  swampy 
lands,  where  the  surface  is  more  or  less  continuously 
under  water,  and  where  such  lands  are  available  under 
suitable  conditions  for  rice  culture,  they  are  largely 
brought  into  requisition  for  this  purpose;  but  the 
seeding  of  the  ground  and  the  harvesting  of  the  crop 
make  it  needful  that  the  fields  shall  be  drained  at 
times  and  at  others  flooded.  Under  these  conditions, 
there  can  be  but  little  waste  from  seepage,  and  the 
chief  demands  for  water  are  created  by  the  loss  from 
evaporation  from  the  surface  of  the  water,  from  the 
growing  crop,  and  from  the  wet  soil  when  the  fields 
have  been  drained,  together  with  the  amounts  which 
are  required  for  reflooding  the  fields  after  they  have 
been  ^rainecl  Occasionally  threatened  attacks  upon 


218  Irrigation   and    Drainage 

the  crop  by  insect  enemies  make  an  extra  flooding  or 
drainage  necessary,  and  this  increases  the  demand  for 
water.  Further  than  this,  in  order  that  the  crop  may 
be  the  best,  the  water  must  not  remain  long  stagnant, 
and  this  requires  either  alternate  flooding  and  drain- 
ing, or  else  a  considerable  steady  surplus  flow  of  water 
over  the  fields. 

In  order  to  secure  more  economical  methods  of 
seeding  and  harvesting  the  rice  fields,  this  crop  is 
extensively  grown  on  naturally  dry  lands,  which  may 
be  readily  checked  off  into  flooding  basins,  to  which 
the  water  may  be  admitted  and  withdrawn  at  pleasure. 
In  these  cases,  there  is  added  to  the  demands  for 
water  already  mentioned  the  loss  from  seepage.  This 
loss  from  seepage  may  be  so  large  that  rice  irrigation 
cannot  be  economically  practiced  on  uplands  unless 
they  are  quite  fine  and  close  in  texture,  so  that  the 
rate  of  seepage  will  be  small,  or  unless  the  normal 
level  of  the  ground -water  is  within  a  few  feet  of  the 
surface.  Even  here  the  subsoil  must  be  pretty  close, 
or  the  loss  of  water  by  under -drainage  will  be  too 
large. 

The  various  available  sources  of  data  regarding  the 
duty  of  water  in  rice  irrigation  place  the  amounts  of 
water  used  as  varying  all  the  way  from  one  second -foot 
for  25,  28,  30,  35,  40,  55  and  66  acres  of  rice,  thus 
making  an  average  of  38.6  acres  per  cubic  foot  of 
water  per  second,  and  this  is  equivalent  to  covering 
the  surface  with  water  about  6.2  inches  deep  every  10 
days. 


Duty   of    Water   on    Water-meadows  219 


THE    DUTY    OF    WATER    ON    WATER-MEADOWS 

In  this  form  of  irrigation,  immense  volumes  of  water  are 
used  on  the  land.  In  Italy,  where  the  practice  has  attained 
the  highest  stage  of  perfection,  where  it  may  have  had  its 
origin,  and  from  which  been  introduced  into  France,  and  even 
into  England  at  the  time  of  the  Roman  invasion,  the  duty  of 
water  appears  to  average  only  about  1.5  acres  per  cubic  foot  per 
second.  On  these  meadows  in  Italy  there  is  maintained  a  nearly 
continuous  flow  of  water,  night  and  day,  from  September  8  to 
March  28  of  each  year,  this  being  the  legal  time  allotted  to 
Marcite,  or  winter-meadow  irrigation. 

The  lands  are  so  laid  out  that  the  roots  of  the  grass  over  the 
whole  meadow  are  continuously  submerged  beneath  a  thin  veil 
of  relatively  warm  running  water,  this  being  turned  off  only  long 
enough  to  cut  the  grass,  which  is  done  two  or  three  times  during 
the  winter  season,  the  green  grass  being  used  for  the  winter  feed 
of  dairy  cows,  which  are  largely  kept  in  the  irrigated  portions  of 
Italy.  So  large  is  the  quantity  of  water  used  during  a  single 
season  on  these  meadows  that  did  none  of  it  drain  away  they 
would  become  submerged  to  a  depth  of  300  feet. 

Carpenter,  quoting  Mangon,  states  that  in  southern  Prance 
and  in  the  Vosges,  where  the  most  careful  measurements  of  the 
water  applied  to  the  meadows  have  been  made,  amounts  are  used 
in  some  cases  sufficient  to  cover  the  surface  1,400  feet  deep  ; 
and  that  of  this  great  volume,  as  much  water  as  160  feet  on  the 
level  sinks  into  and  percolates  through  the  soil  of  the  field  during 
a  winter  season.  But  even  in  the  summer  irrigation,  as  much  as 
374  feet  of  \»ater  on  the  level  are  applied  between  April  and 
July,  while  of  this  amount  no  less  than  88  feet  percolates  into 
the  ground  or  is  evaporated. 

The  meadows  upon  which  these  large  volumes  of  water  are 
applied  are  usually  permanent  ones,  and  have  had  their  surfaces 
fitted  with  the  greatest  care,  so  that  the  relatively  warm  water 
may  be  kept  steadily  flowing  over  the  surface  about  the  roots  of 
the  grass  in  a  thin  veil  until  it  is  ready  to  cut,  when  it  is  turned 
off  only  long  enough  to  remove  the  crop. 


220  Irrigation   and    Drainage 

In  Italy  these  heavy  and  continuous  irrigations  stimulate 
the  grass  to  grow  the  year  round,  and  in  the  vicinity  of  Milan, 
where  the  irrigation  canals  are  led  through  and  beneath  the 
city,  relieving  it  of  all  its  sewage,  this  warm  and  highly  ferti- 
lizing water  so  stimulates  the  growth  of  grass  that  seven  heavy 
crops  are  taken  from  the  ground  each  year,  aggregating,  accord- 
ing to  Baird  Smith,  45  to  50  tons  per  acre,  and  in  exceptional 
cases  one -half  more  than  this. 

It  will  be  readily  understood  that  the  application  of  water 
to  these  winter  and  summer  water-meadows  in  such  large  vol- 
umes has  quite  a  distinct  purpose  from  that  of  supplying  the 
needed  moisture  for  the  transpiration  of  the  grasses.  In  short, 
the  practice  has  been  found  to  be  a  sure  way  of  greatly  pro- 
longing the  growing  season  of  each  year,  and  a  cheap  means  of 
permanently  maintaining  a  high  state  of  fertility  of  the  soil. 


THE  DUTY  OF  WATER  IN  CRANBERRY  CULTURE 

In  the  irrigation  of  cranberries,  as  in  the  case  of  rice  and 
water-meadows,  the  purpose  of  the  treatment  is  quite  distinct 
from  that  of  ordinary  irrigation.  It  is  true  that  this  crop 
demands  a  large  amount  of  water,  but  its  normal  habitat  is  such 
that  ordinarily  it  is  abundantly  supplied  by  natural  sub -irri- 
gation. In  this  case,  the  water  is  demanded  chiefly  to  protect 
the  crop  against  the  ravages  of  insects  and  injury  from  frost, 
and  to  prevent  winter -killing. 

As  the  surface  of  the  ground-water  is  seldom  more  than  one 
to  two  feet  below  the  surface  of  the  bog,  and  as  the  peat  and 
muck  above  the  water  are  at  all  times  nearly  saturated,  the 
amount  of  water  required  for  cranberry  irrigation  is  but  little 
more  than  that  necessary  to  submerge  the  vines,  which  will 
rarely  be  more  than  .8  to  1.5  acre-feet.  But,  except  for  the 
flooding  for  winter  protection,  the  demands  for  water  are  so 
peremptory  and  the  time  so  short  which  can  be  allowed  for  sup- 
plying it,  that  but  a  low  duty  is  possible  when  this  is  measured 
by  the  rate  at  which  the  water  must  be  delivered. 


Duty    of    Water   in    Cranberry  Culture          221 

When  it  is  protection  against  frost  which  is  required,  the 
marsh  must  be  given  as  much  as  4  to  6  inches  of  water  on  the 
level  in  nearly  as  many  hours.  To  do  this  will  require  a  stream 
of  1  to  1.3  cubic  feet  per  second  per  acre.  But  when  the  flood- 
ing is  to  destroy  insects,  the  haste  need  not  be  so  great  ;  while 
for  winter  flooding,  a  relatively  small  stream  will  answer  the 
needs,  as  six  weeks,  if  need  be,  may  be  taken  in  the  flooding, 
and  as  the  ground-water  surface  around  the  marsh  is  usually 
above  the  marsh  itself,  the  loss  from  seepage  is  small,  as  must 
also  be  that  by  evaporation  during  the  winter. 


CHAPTER  VI 

FREQUENCY,   AMOUNT  AND    MEASUREMENT   OF   WATER 
FOR    SINGLE   IRRIGATIONS 

To  have  become  able  to  apply  water  to  crops  at 
the  right  time,  in  the  right  amounts  and  in  the  best 
manner  is  to  have  attained  the  acme  of  the  art  of 
irrigation.  Unfortunately,  it  is  no  more  possible  to 
bear  a  man  to  this  position  on  the  vehicle  of  language 
than  it  is  a  cook  to  the  art  of  making  the  best  bread. 
Both  arts  are  founded  upon  the  most  rigid  of  laws, 
which  may  be  readily  and  certainly  followed  when  the 
conditions  have  been  learned.  But  the  minutiae  of 
essential  details  are  so  extreme  that  words  fail  utterly 
to  convey  them  to  the  mind,  and  they  must  be  per- 
ceived through  the  senses,  to  be  grasped  with  such 
clearness  as  to  lead  unerringly  to  the  right  results. 
There  are,  however,  general  principles  underlying  the 
art,  which  may  be  readily  stated,  and,  when  com- 
prehended, place  one  in  position  to  more  quickly  grasp 
the  details  essential  to  complete  success  in  the  appli- 
cation of  water  to  crops. 

THE    AMOUNT    OF    WATER    FOR    SINGLE    IRRIGATIONS 

In  humid  climates,  there  is  always  more  or  less 
soil -leaching,  resulting  from  super -saturation  of  the 

(222) 


Amount   of   Water  for   Single  Irrigations      223 

soil  during  times  of  heavy  or  protracted  rains.  This 
leaching  is  usually  looked  upon  as  a  necessary  evil, 
which  results  in  a  waste  of  fertility.  Whether  this 
conviction  is  well  founded,  or  whether  a  certain 
amount  of  soil  washing  is  indispensable  to  unim- 
paired fertility,  it  appears  to  the  writer  is  one  of 
the  important  soil  problems  awaiting  positive  demon- 
stration. The  accumulation  of  alkalies  in  the  soils 
of  arid  climates,  where  relatively  small  leaching  is 
associated  with  large  evaporation,  and  the  tendency 
of  alkalies  to  become  intensified  where  irrigation  has 
been  long  practiced,  are  facts  which  suggest  that 
there  may  be  such  a  thing  as  too  great  economy  of 
water  in  irrigation. 

But,  waiving  this  possibility  of  demand  for  water, 
and  all  of  those  cases  where  the  water  is  applied  for 
other  purposes  than  meeting  the  ordinary  needs  of 
vegetation,  the  fundamental  conditions  which  deter- 
mine the  amount  of  water  which  should  be  applied  at 
a  single  irrigation  are:  (1)  the  capacity  of  the  soil 
and  subsoil  to  store  capillary  water;  (2)  the  depth 
of  the  soil  stratum  penetrated  by  the  roots  of  the 
particular  crop  ;  (3)  the  rate  at  which  the  soil  below 
the  root  zone  may  supply  water  by  upward  capillarity 
to  the  roots ;  and  (4)  the  extent  to  which  the  soil 
and  subsoil  have  become  dried  out. 

On  the  other  hand,  the  conditions  which  determine 
the  frequency  of  irrigation  are :  (1)  the  amount  of 
available  moisture  which  may  be  stored  in  the  soil ; 
(2)  the  rate  at  which  this  moisture  is  lost  through 
the  crop  and  through  the  soil;  and  (3)  the  degree 


224  Irrigation   and    Drainage 

of  desiccation  of  the  soil  which  the  particular  crop 
will  tolerate  before  serious  interference  to  growth  re- 
sults. 

THE    CAPACITY    OF    SOILS    TO    STORE    WATER 
UNDER    FIELD    CONDITIONS 

The  amount  of  water  which  may  be  stored  in  soils  under 
field  conditions  varies  between  wide  limits  with  the  character 
and  texture  of  the  soils,  and  also  with  the  distance  of  standing 
water  in  the  ground  below  the  surface. 

When  a  fine  sand  will  hold  in  the  first  foot  above  the 
ground- water  23.86  per  cent  of  its  dry  weight  of  water,  at  4  feet 
above  it  was  found  to  hold  only  8.12  per  cent,  and  8  feet  above 
only  3.14  per  cent  of  the  dry  weight.  When  these  amounts  are 
expressed  in  pounds  per  cubic  foot,  they  stand  only  a  little  more 
than  23.86  pounds,  8.12  pounds,  and  3.14  pounds,  a  cubic  foot 
of  the  dry  sand  weighing  about  105  pounds. 

In  the  case  of  a  natural  field  soil  of  sandy  clay  loam  with 
clay  subsoil  changing  to  a  sand  at  4  feet,  and  where  the 
ground -water  changed  during  the  season  from  7.6  feet  below 
the  surface  to  8.4  feet,  the  water  content  of  the  soil  was  found 
to  be  as  follows: 


1st  ft. 

2dft. 

3d  ft. 

4th  ft. 

5th  ft. 

6th  ft. 

7th  ft. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

water 

water 

water 

water 

water 

water 

water 

July  25 

10.44 

16.91 

14.81 

10.38 

7.82 

13.66 

22.29 

October  2 

9.49 

16.27 

14.41 

6.99 

7.74 

7.85 

19.35 

Loss  .95  .64  .4  3.39  .08  5.81  2.94 

During  this  interval  there  had  been  a  rainfall  of  10.84 
pounds  per  square  foot.  There  is  no  doubt  that  in  the  upper 
4  feet  a  considerable  part  of  the  water  was  lost  through  surface 
evaporation.  It  is  quite  likely,  also,  that  a  portion  of  the  loss 
shown  in  the  5th,  6th,  and  7th  feet  was  due  to  an  upward  capil- 
lary movement.  But  there  is  little  reason  to  doubt  that  the 


Amount   of   Water  for   Single   Irrigations      225 

chief  loss  shown  in  the  lower  three  feet  is  due  to  downward 
drainage  or  percolation,  owing  to  a  lowering  of  the  ground- 
water  surface. 

The  8 -foot  column  of  fine  sand,  referred  to  above,  lost  water 
by  percolation  in  22  hours  and  46  minutes,  after  full  saturation, 
equal  to  6.35  per  cent  of  the  dry  weight  of  the  whole  column  ; 
and  as  this  must  have  come  almost  wholly  from  the  upper  4 
feet,  the  water  there  must  have  been  reduced  in  that  time  more 
than  12  per  cent,  which  would  leave  a  saturation  of  only  8 
per  cent. 

But  as  plants  would  suffer  severely  for  water  in  a  soil  of 
this  texture  when  the  moisture  was  brought  down  to  4  per  cent, 
it  is  plain  that  only  from  2  to  4  per  cent  of  the  weight  of  such 
a  soil  can  be  added  at  one  irrigation  without  entailing  severe 
loss  by  percolation  below  the  depth  of  root-feeding.  Taking  a 
cubic  foot  of  such  a  soil  at  105  pounds,  the  maximum  irrigation 
which  could  be  applied  without  severe  loss,  supposing  the  ground 
to  be  wet  down  5  feet  and  the  soil  to  have  dried  3  per  cent, 
would  be  15.75  pounds  per  square  foot,  or  2.86  inches  in  depth. 
The  sand  in  question,  however,  is  more  open  than  most  agri- 
cultural soils;  hence  it  follows  that  more  than  2  inches  of  water 
may  be  safely  applied  at  one  irrigation  to  any  crop  much  in 
need  of  water. 

By  taking  samples  of  soil  in  a  field  of  maize  and  clover 
when  the  corn  leaves  were  badly  curled  and  when  clover  wilted 
quite  early  in  the  forenoon,  the  following  moisture  conditions 
were  found: 


Soil  moisture  relations  when  growth  is  brought  to  a  standstill 

Depth  of  sample                                      Clover  Maize  Fallow  ground 

PER  CENT  PEE  CENT  PER  CENT 

0-6    in.  clay  loam 8.39  697  16.28 

6-12    "       "        "      8.48  7.8  17.74 

12-18    ' '    reddish  clay 12.42  U.6  19.88 

18-24    "          "           "     13.27  11.98  19.84 

24-30    "    sandy  clay 13.52  10.84  18.56 

40-43    "    sand...                                            9.53  4.17  15.9 


226  Irrigation   and    Drainage 

The  moisture  contained  in  the  fallow  ground,  determined  at 
the  same  time,  shows  how  much  water  such  a  soil  may  hold 
against  a  drought  and  against  percolation  below  root  action. 

The  amount  of  moisture,  too,  in  this  fallow  ground  happens 
to  stand  just  at  the  under  limit  for  most  vigorous  plant -growth 
in  this  type  of  soil,  while  the  upper  limit  is  given  in  the  table 
below  for  comparison : 

Showing  upper  and  lower  limits  of  best  amount  of  soil  moisture  for  one  type  of  soil 

Kind  and  depth  Lower  limit  of       Upper  limit  of         Available 

of  soil  soil  moisture          soil  moisture       soil  moisture 

PER  CENT  PEE  CENT        LBS.  PKB  CU.  FT. 

Clay  loam,  first  foot 17.01  25.77  6.92 

Reddish  clay,  second  foot 19.86  24.3  4.112 

Sandy  clay,  third  foot 18.56  24.03  5.722 

Sand,  fourth  foot 15.9  22.29  6.786 

Total 23  55 

It  will  be  seen  from  this  table  that  to  bring  the  surface  four 
feet  of  soil  from  the  lower  limit  of  the  best  productive  stage  of 
water  content  to  the  upper  limit  requires  an  application  of  23.55 
pounds  per  square  foot,  or  a  depth  of  irrigation  equal  to  4.527 
inches. 

It  is  quite  certain  that  with  a  greater  distance  to  standing 
water  in  the  ground,  the  4th  foot,  and  probably  also  the  3d  foot, 
could  not  have  retained  the  amount  of  water  shown  by  the  table  ; 
and,  hence,  that  an  irrigation  of  4.5  inches  on  such  a  soil  would 
have  resulted  in  some  loss  by  percolation  below  the  depth  of 
root  feeding. 

If  it  should  happen  that  a  soil  like  the  one  in  question  be- 
came as  dry  as  is  shown  in  the  table  on  page  225,  then  the  depth 
of  irrigation  required  to  bring  the  moisture  content  up  to  the 
upper  limit  of  productiveness  would  be  for  the  maize  11.37  inches, 
and  for  the  clover  9.39  inches,  supposing  the  ground- water  to  be 
at  the  time  not  more  than  7  feet  below  the  surface. 

It  follows,  therefore,  from  the  observations  and  data  pre- 
sented, that  the  amount  of  water  required  for  one  irrigation, 
where  the  soil  has  not  been  permitted  to  become  too  dry,  and 


Depth   of  Root   Penetration  227 

where  the  aim  is  to  bring  the  soil  moisture  to  the  upper  limit 
of  productiveness  without  causing  percolation  below  4  or  5  feet, 
will  range  from  about  2.5  inches  on  the  most  open  soils  to  4.5 
inches  on  soils  of  average  texture.  But  when  excessive  drying 
of  the  soil  has  taken  place,  then  the  amount  of  water  applied 
may  range  from  3.75  inches  on  the  most  open  soils  to  as  high  as 
even  11  inches  on  that  which  is  of  medium  or  fine  texture.  It 
should  be  understood  that  many  soils,  when  they  become  very 
dry,  develop  shrinkage  cracks,  which  permit  very  rapid  and  ab- 
normally large  percolation  if  excessive  amounts  of  water  are 
applied  at  one  time,  and  this  without  saturating  the  soil,  the 
water  simply  draining  through  the  large  open  channels.  In  such 
cases  repeated  smaller  applications  of  water  will  ensure  less  loss 
by  percolation,  permitting  the  soil  to  expand  and  close  up  the 
shrinkage  cracks. 


THE  DEPTH  OP  ROOT  PENETRATION 

The  greater  the  depth  to  which  the  roots  of  a 
crop  may  feed  to  advantage  in  the  soil,  the  larger 
may  be  the  amount  of  water  applied  to  the  field  at  a 
single  irrigation  without  any  passing  beyond  the  zone 
of  root  action,  simply  because  2  feet  of  soil  will  store 
more  water  than  1  foot,  and  10  feet  more  than  5.  But, 
further  than  this,  where  the  roots  of  a  plant  penetrate 
the  soil  deeply  and  spread  widely,  a  much  smaller  per 
cent  of  water  in  the  soil  will  enable  the  plant  to  ob- 
tain enough  to  carry  on  its  functions  to  good  advan- 
tage. This  is  so  because  the  roots  go  to  the  moisture, 
and  do  not,  therefore,  need  to  wait  for  the  moisture  to 
come  to  them  at  the  extremely  slow  rate  it  is  known 
to  travel  in  a  relatively  dry  soil.  Then,  too, when  a  crop, 
by  reason  of  its  great  spread  of  root,  is  able  to  meet 


228 


Irrigation   and    Drainage 


Fig.  37.    Penetration  of  roots  of  prune  on  peach  in  arid  soil  of 
California.     (Hilgard.) 


Depth   of  Root   Penetration 


229 


its  needs  in  a  dryer  soil,  it  is  evident  that  a  much 
higher  duty  of  water  is  possible,  for  the  simple  reason 
that  none  can  be  lost  by  percolation,  and  much  less 
will  be  lost  by  surface  evaporation,  even  with  deficient 
tillage. 

We   have   already  called  attention  to  the   probable 
deeper  rooting  of  plants  in  soils  of  arid  regions,  where 


Fig.  ;J8.    Penetration  of  apple  root  in  Wisconsin,  7  years  planted. 
Depth  9  feet.     (Goff.) 

there  is  less  distinction  between  the  soil  and  subsoil, 
than  in  those  of  humid  climates.  Since  writing  that 
section,  we  have  received  Professors  Hilgard  and 
Loughridge's  Bulletin  121,  in  which  they  emphasize 
this  point  by  placing  in  evidence  a  photo -engraving 
of  a  prune  tree  on  a  peach  root  exposed  in  the  soil 
to  a  depth  of  8  feet,  and  represented  in  Fig.  37.  The 
method  they  have  used  in  exposing  the  root  appears, 


230 


Irrigation   and.    Drainage 


from  the  photograph,  to  have  destroyed  nearly  all  but 
the  main    trunks,  unless  it  was    true    that   the   active 


Fig.  39. 


Penetration  of  grape  roots  in  Wisconsin  soil. 
Depth  6  feet.     (Goff.) 


absorbing  surfaces  were  chiefly  still  more  deeply  buried 
in  the  soil  than  the  excavation  extended.  This  appears 
quite  likely  to  have  been  the  case,  for  this  penetra- 


Depth   of  Root  Penetration 


231 


tion   is   no   greater  than  has  been  found  in  soils  in 
Wisconsin. 


Fig.  40.    Penetration  of  raspberry  roots  in  Wisconsin  soil. 
Depth  5  feet.     (Goff.) 

Professor  Goif  has  washed  out  the  roots  of  the 
apple,  grape,  raspberry  and  strawberry,  showing  the 
extent  of  their  development  in  a  loamy  clay  soil 


232 


Irrigation   and    Drainage 


underlaid  by  a  reddish  clay  subsoil,  which  changed 
through  a  sandy  clay  into  a  mixed  sand  and  gravel, 
at  4  or  more  feet.  His  photographs,  reproduced  in 
Figs.  38,  39,  40  and  41,  show  to  what  extent  the  roots 
of  these  fruits  penetrate  the  soils  and  subsoils  of 


Fig.  41.    Penetration  of  roots  of  strawberry  in  matted  rows  in  Wisconsin 
soil.    Depth  22  inches.     (Goff.) 

Wisconsin,  where  the  annual  rainfall  ranges  from  28 
to  40  inches.  It  will  be  seen  from  the  legends  that 
the  roots  of  the  apple  have  extended  to  a  depth  of 
fully  9  feet,  the  grape  more  than  6,  and  the  raspberry 
more  than  5.  It  is  plain,  therefore,  that  even  in  the 
soils  of  humid  climates  the  roots  penetrate  so  deeply 
that  the  moisture  of  the  surface  8  to  10  or  12  feet  is 


Depth  of  Root   Penetration 


233 


laid  under  tribute  by  them,  and 
this  makes  it  clear  that  the  stor- 
age room  for  water  in  the  soil  for 
many  of  the  fruits  may  be  much 
greater  than  we  have  pointed  out 
above. 

In  the  case  of  the  strawberry, 
however,  the  figure  shows  that  it 
is  a  particularly  shallow  feeder, 
and,  therefore,  is  certain  to  suffer 
severely  in  dry  times  if  not  irri- 
gated. 

In  Fig.  42  are  shown  the  roots 
of  alfalfa  only  174  days  from 
seeding.  These  had  forged  their 
way  through  so  close  a  clay  subsoil 
that  more  than  four  days  of  con- 
tinuous washing  were  required  to 
dissolve  away  a  cylinder  of  soil  1 
foot  in  diameter  and  4  feet  long. 
The  roots,  however,  had  penetrated 
this  soil  to  a  depth  exceeding  four 
feet,  and  the  nitrogen-fixing  tuber- 
cles were  already  developed  22 
inches  below  the  surface. 

In  the  rigid  data  here  pre- 
sented, combined  with  that  shown 
in  Figs.  10  and  11,  we  have  a 
rational  basis  upon  which  to  build 
a  practice  of  irrigation,  so  far  as 
that  relates  t<?  the  depth  of  soil 


Fig.  42.  Roots  of  alfalfa 
in  Wisconsin  174  days 
from  seeding. 


234  Irrigation   and    Drainage 

which  may  be  moistened  and   yet  be  within  the  reaclr 
of  plants. 

THE    FREQUENCY    OF    IRRIGATION 

The  data  presented  in  the  last  two  sections  are  a 
portion  of  those  required  to  understand  the  rationale 
of  this  important  subject.  Viewed  from  the  standpoint 
of  labor  involved  in  distributing  water  for  irrigation, 
it  is  evident  that  the  fewer  the  number  of  irrigations 
the  smaller  may  be  the  labor  involved  and  the  lower 
the  cost.  Moreover,  the  less  often  the  surface  of  the 
soil  is  wet,  the  smaller  will  be  the  loss  of  water  by 
evaporation  and  by  seepage  in  bringing  the  water 
to  the  fields  ;  hence,  the  higher  will  be  the  duty  of 
water. 

The  most  general  rule  which  can  be  laid  down 
governing  the  frequency  of  irrigations  and  the  amount 
of  water  to  be  applied  at  one  time,  is  to  apply  as  much 
water  to  the  soil  which  is  available  to  the  crop  as  the 
crop  will  tolerate  without  suffering  in  yield  or  quality, 
and  then  husband  this  water  with  the  most  thorough 
tillage  practicable,  in  order  to  reduce  the  number  of 
irrigations  to  the  minimum. 

It  has  been  shown  that  a  crop  of  maize  yielding 
70  bushels  per  acre  may  be  brought  to  maturity  in  110 
days  with  11.75  acre-inches  of  water.  It  has  also  been 
shown  that  a  soil  of  medium  texture  may  carry  in  the 
surface  4  feet  4.5  inches  of  available  water,  or,  if  ex- 
tremely open,  2.5  inches.  Could  so  high  a  duty  of 
water  as  this  be  attained  under  field  conditions,  three 


Frequency  of  Irrigation  235 

irrigations  would  be  required  for  such  a  crop  of  maize 
on  the  medium  soil  and  five  on  the  most  open  one, 
making  the  intervals  between  waterings  37  and  22  days; 
but  if  the  yield  was  100  bushels  per  acre  instead  of 
70,  the  number  of  irrigations  required  would  be  four 
or  seven,  and  the  intervals  between  waterings  would  be 
27  days  for  the  medium  soil  and  15  days  for  the  most 
open  one. 

Computing  for  wheat  on  a  similar  basis,  with  a 
yield  of  40  bushels  per  acre,  requiring  12  acre-inches 
of  water  under  the  conditions  of  the  highest  duty,  the 
number  of  irrigations  would  have  to  be  three  or  five, 
at  intervals  of  33  or  20  days,  according  as  the  texture 
of  the  soil  was  medium  or  very  coarse;  while  a  crop 
of  barley  yielding  60  bushels  per  acre  in  a  period  of 
88  days  would  need  12.84  acre -inches,  to  be  applied  in 
three  or  five  irrigations,  at  intervals  of  29  or  18  days. 

These  three  cases  may  be  taken  as  types  of  the 
highest  limits  likely  to  be  attained  under  the  best  of 
field  conditions,  and  they  may  serve  as  standards 
toward  which  we  may  strive  with  the  satisfaction  of 
knowing  that  extremely  good  and  thorough  work  has 
been  done  if  they  are  attained. 

It  will  be  desirable,  now,  to  review  the  literature  of 
the  frequency  of  irrigation,  and  see  how  actual  practice 
in  various  parts  of  the  world  corresponds  with  the 
conclusions  stated. 

In  southern  Europe,  wheat  is  irrigated  three  to  four 
times;  in  India,  five  times  during  the  hot  seasons  and 
four  times  for  the  crop  of  the  cool  season.  In  the 
United  States,  Colorado  irrigates  two,  three  and,  occa- 


236  Irrigation   and    Drainage 

sionally,  four  times,  two  being  the  usual  number ;  in 
New  Mexico,  the  ground  is  irrigated  once  before  and 
once  after  seeding  and  five  times  later,  making  seven 
times  in  all ;  while  in  Utah  the  number  of  waterings  is 
three  to  five. 

The  average  number  of  irrigations  appears  to  be 
from  three  to  five  for  wheat  in  all  parts  of  the  world. 
But  it  should  be  understood  that  these  irrigations  are, 
in  all  cases,  supplemented  more  or  less  with  natural 
rainfall.  In  Colorado,  for  example,  where  the  usual 
number  of  irrigations  is  two,  the  rainfall  from  April  1 
to  July  1  is  often  as  great  as  8  inches,  or  two-thirds 
the  amount  of  water  required  for  a  yield  of  40  bushels 
per  acre,  thus  making  the  number  of  irrigations  amount 
practically  to  six  rather  than  two,  and  the  mean  interval 
16%  days,  instead  of  33  to  20. 

It  must  be  remembered,  further,  that  while  the 
irrigations  of  wheat  are  in  all  cases  supplemented  with 
natural  rainfall,  the  yield  per  acre  does  not  average  40 
bushels ;  hence  the  agreement  of  the  theoretical  fre- 
quency of  irrigation,  33  to  20  days,  with  that  actually 
practiced  is  more  apparent  than  real. 

In  Egypt,  maize  is  irrigated  every  15  days,  which 
would  make  seven  waterings  for  the  crop.  Barker  states 
that  six  irrigations  are  given  to  a  crop  in  the  Mesilla 
valley,  New  Mexico;  while  in  Italy  three  is  the  usual 
number.  But  here,  again,  the  spring  and  early  summer 
rainfall  is  quite  large;  so  large,  indeed,  that  much  maize 
is  grown  without  irrigation.  It  appears,  therefore,  that 
where  this  crop  must  really  depend  upon  irrigation 
for  the  water  needed,  it  must  be  applied  as  often  as 


Frequency  of  Irrigation  237 

every  15  to  20  days,  and  our  experimental  studies  place 
it  at  15  to  27  days  for  yields  of  100  bushels  per  acre. 

The  intervals  between  the  irrigations  for  other 
cereals  will  be  found  to  fall  between  those  for  wheat 
and  maize,  oats  requiring  the  largest  amount  of  water 
and  barley  the  least,  to  mature  a  large  crop. 

In  the  irrigation  of  clover  and  alfalfa,  the  usual 
practice  is  to  irrigate  once  for  each  crop.  But  there  is 
little  question  that  larger  yields  for  each  crop  may  be 
secured  where  the  number  of  irrigations  is  doubled, 
giving  six  where  the  number  of  crops  is  three,  and  ten 
where  it  is  five,  thus  making  the  length  of  the  interval 
10  or  20  days.  . 

With  other  meadows,  the  general  custom  is  to  give 
these  as  much  and  as  many  waterings  as  the  water 
supply  will  permit.  In  Italy,  the  summer  meadows  are 
watered  every  14  days.  In  southern  France  they  are 
watered  every  5  to  18  days,  and  on  the  average  every 
10  days.  Winter  water  meadows,  as  has  been  stated, 
are  watered  with  a  nearly  continuous  flow  of  water  over 
their  surfaces. 

With  potatoes,  the  custom  is  usually  to  depend  upon 
the  natural  rainfall  to  bring  the  crop  nearly  or  quite 
to  blossoming,  and  then  to  irrigate  twice  on  nearly 
level  fields,  and  three  to  four  times  where  the  slopes  are 
steep  or  where  the  soil  is  very  porous  and  coarse  in 
texture,  thus  making  an  interval  for  this  crop  of  20 
to  40  days. 

For  this  crop  our  experimental  studies  indicate  that 
8.24  acre- inches  may  produce  400  bushels  per  acre  ; 
hence,  that  two  to  four  irrigations  might  be  sufficient 


238  Irrigation   and    Drainage 

for  a  full  season,  starting  with  the  ground  in  good  con- 
dition as  regards  moisture  at  time  of  planting,  making 
the  possible  interval  33  to  65  days. 

Fruit  trees  in  Sicily  and  southern  Italy  are  watered 
12  to  25  times  during  one  season  or  once  every  7  to  14 
days.  The  peach  and  apple  in  Mesilla,  New  Mexico,  are 
watered  once  at  the  beginning  of  winter,  once  early  in 
January,  and  four  or  five  times  between  April  1  and 
September  30,  thus  making  the  interval  for  the  growing- 
season  30  to  40  days.  In  Algeria  and  Spain,  oranges 
are  irrigated  the  year  round — every  15  days  in  spring 
and  summer,  but  at  longer  intervals  the  balance  of  the 
year ;  and  it  is  only  on  the  heavy  soils  that  irrigation 
is  dispensed  with  during  the  rainy  season.  Grapes, 
when  irrigated,  are  usually  watered  every  10  to  20 
days,  and  young  vineyards  oftener  than  those  more 
mature. 

Rice  in  Italy  is  kept  flooded  from  the  time  of 
seeding  until  the  plants  are  coming  into  bloom,  and 
then  the  water  is  drawn  off,  but  the  fields  are  irrigated 
afterwards  every  few  days.  In  Egypt  the  water  in 
the  rice  basins  is  changed  every  15  days,  and  in  India 
a  crop  of  rice  gets  as  many  as  twelve  waterings. 

In  South  Carolina,  Mr.  Hazzard  informs  me  that 
their  custom  is  to  clay  the  seed  to  prevent  it  from 
floating,  and  then  to  flood  the  fields,  keeping  them  so 
until  the  rice  is  well  up,  when  the  water  is  drawn  off 
for  3  days  to  allow  the  plants  to  become  rooted  in 
the  soil,  when  the  fields  are  again  flooded  for  3  weeks, 
but  changing  the  water  every  7  days.  The  water 
is  again  drawn  off  for  30  days,  to  give  the  fields  two 


Measurement   of  Water  239 

dry   hoeings,  when  flooding   is   again   resorted   to  and 
maintained  until  the  crop  is  matured. 

THE    MEASUREMENT    OF    WATER 

The  man  who  has  become  expert  in  handling  water 
for  irrigation  really  needs  no  means  for  measuring 
the  amount  required  for  the  watering.  His  judg- 
ment, based  upon  an  examination  of  the  soil,  is  more 
reliable  as  to  when  enough  has  been  applied  than  any 
measurement  which  could  be  made.  But  as  soon  as 
the  same  source  of  water  becomes  the  joint  property 
of  a  community,  or  wherever  water  is  sold  to  consumers, 
means  for  measurement  and  division  become  indis- 
pensable. For  the  user  of  water,  too,  a  definite  knowl- 
edge of  the  exact  amount  he  is  putting  upon  a  given 
area  of  land  is  very  important,  until  he  comes  to  know 
the  needs  of  his  land  and  of  his  crops  for  water ;  be- 
cause without  this  knowledge  he  is  liable  to  run  on 
for  years,  using  too  much  or  too  little  water,  leading  the 
water  too  slowly  or  too  rapidly  through  the  furrows, 
causing  waste  by  deep  percolation  or  too  shallow  wet- 
ting of  the  soil.  If  he  knows  that  he  has  put  the 
equivalent  of  3  inches  of  water  upon  his  field  and  only  a 
quarter  of  the  surface  has  been  wet,  it  is  certain  that 
his  method  has  been  faulty  and  a  large  part  of  the 
water  used  has  been  lost. 

UNITS    OF    MEASUREMENT 

From  the  standpoint  of  the  agriculturist,  there  is 
no  unit  for  the  measurement  of  water  used  in  irrigation 


240  Irrigation   and    Drainage 

so  satisfactory  as  one  which  expresses  the  depth  of 
water  to  be  applied  to  a  unit  area,  and  the  acre -inch 
for  English-speaking  people,  or  the  hectare -centimeter 
for  those  who  use  the  metric  system,  should  become 
universal.  Rainfall  is  now  universally  measured  in 
units  of  depth,  and,  as  irrigation  is  intended  to  make 
good  deficiencies  of  rainfall,  it  would  simplify  matters 
greatly  if  the  irri gator  could  call  for  the  depth  of  water 
he  desired. 

An  acre-inch  is  enough  water  to  cover  1  acre  1  inch 
deep;  and  10  acre -inches  of  water  is  enough  to  cover  1 
acre  10  inches  deep,  or  10  acres  1  inch  deep.  As  an 
acre  contains  43,560  square  feet,  12  acre-inches  is  equal 
to  43,560  cubic  feet  of  water,  and  1  acre -inch  equals 
one -twelfth  of  this  amount,  or  3,630  cubic  feet.  As 
there  are  1,728  cubic  inches  in  a  cubic  foot,  and  231 
cubic  inches  in  a  gallon,  1  cubic  foot  equals  7.48+ 
gallons,  and  1  acre -inch  equals  27,150  gallons. 

As  1  cubic  foot  of  water  at  60°  F.  weighs  62.367 
pounds,  1  acre-inch  equals  226,392  pounds,  or  113.2 
tons  of  2,000  pounds. 

Another  measure  frequently  used  in  the  gauging  of 
streams,  and  also  used  as  an  irrigation  unit,  is  the 
second- foot,  which  means  a  discharge  or  flow  of  water 
equal  in  volume  to  1  cubic  foot  per  second  of  time; 
and  a  stream  having  the  volume  of  1  second -foot  would 
supply  an  acre -inch  in  3,630  seconds,  or  in  30  seconds 
more  than  one  hour.  In  24  hours,  a  stream  of  ] 
second-foot  would  supply  23.8  acre -inches,  and  would 
cover  7.93  acres  of  land  with  water  3  inches  deep. 

Still   another  unit   in   common   use  in  the  western 


Measurement   of  Water  241 

United  States  is  the  miner's  inch,  which  is  the  amount 
of  water  which  may  flow  through  an  opening  1 
square  inch  in  section  in  one  second  under  a  certain 
pressure  or  head.  But  the  legal  pressure  varies  in 
different  states ;  hence,  the  miner's  inch  has  not  a 
fixed  and  definite  value.  In  California  50  miner's 
inches  are  usually  counted  equivalent  to  1  second -foot, 
while  in  Colorado  only  38.4  statute  inches  are  required 
for  a  second -foot. 

Where  a  larger  unit  of  measure  is  desired  than 
either  of  those  named,  the  acre-foot  is  sometimes 
used.  This  is  an  amount  of  water  required  to  cover 
an  acre  1  foot  deep,  and  is,  therefore,  equal  to  12 
acre -inches. 

METHODS  OF  MEASUREMENT  OF  WATER 

Much  and  long  as  irrigation  has  been  practiced,  and  impor- 
tant as  the  subject  is,  especially  in  communities  where  water 
is  scarce  and  where  each  user  has  need  of  every  drop  of  water 
he  can  get,  there  appears  even  yet  to  have  been  devised  few 
methods  of  measuring  or  of  apportioning  water  among  the  users 
which  possess  the  degree  of  precision  which  could  be  desired. 

In  the  case  of  individual  irrigators,  where  the  water  is 
pumped  and  stored  in  reservoirs,  to  be  used  as  desired,  the  area 
of  the  reservoir  and  the  amount  the  water  is  lowered  in  it  fur- 
nish the  needed  data  for  determining  the  amount  which  has 
been  applied  to  ,a  given  area  of  land.  Or,  in  the  case  of  direct 
application  of  the  water  pumped  to  the  land,  the  rate  of  the 
pump  may  be  known,  and  thus,  through  a  knowledge  of  the  time 
of  pumping,  furnish  an  approximate  measure  of  the  water  used. 
In  the  great  majority  of  cases,  however,  a  knowledge  of  the 
amount  of  water  used  in  irrigation  must  be  gained  in  some  other 
way. 


242 


Irrigation    and    Drainage 


The  Method  of  Time  Division 

Where  the  amount  of  water  carried  in  a  ditch,  lateral  or 
pipe  is  not  so  large  but  that  an  individual  may  use  the  whole 
of  it  to  advantage,  the  usual  and  the  simplest  method  of  divid- 
ing the  water  is  on  the  basis  of  time,  allowing  each  user  to 
have  the  whole  stream  a  specified  number  of  hours  and  minutes, 
making  the  length  of  the  time  proportional  to  the  amount  of 
water  to  which  each  user  is  entitled. 

With  this  method,  it  is  customary  to  issue  to  the  various 
users  under  the  ditch,  at  the  beginning  of  the  irrigation  season, 
printed  schedules  or  tickets,  covering  the  whole  or  a  portion  of 
the  season,  which  specify  the  dates  upon  which  they  will  be 
entitled  to  the  use  of  water,  and  the  length  of  time  they  can 
have  it,  as  illustrated  by  the  following  ticket: 


!  WATER  TICKET  NO-J^T. 

|  DISTRICT  NO./£...~ DITCH  NO-& ~ 

Springville.  ^...CjfaX.32 1896J 

»    X 


^  Veu  •»  then  vequlved  to  discontinue  Ite  use  and  tui>n  It  ofl  your  land. 

{  WBUTBR    BIRD.    Wet.rm«.t.I.. 

* , Deputy. 

jJrjJXT^TT^rv^S  ^^Z^7^^r^7^7^7^3^-2^,3^^7^7^S-2^VZ^A7^r-ZJ^7^r-I»l 


With  this  system,  if  one  man  is  entitled  to  two,  three  or 
four  times  the  amount  of  water  that  a  neighbor  is  entitled  to, 
the  length  of  his  period  is  two,  three  or  four  times  as  long: 
and,  as  shown  by  the  ticket,  a  regular  rotation  is  followed,  the 
water  returning  to  the  same  user  after  the  same  number  of 
days. 

Where  the  water  must  be  used  day  and  night,  as  should  be 
the  case  where  water  is  scarce  and  is  allowed  to  run  continuously 
to  reduce  waste,  in  order  to  prevent  the  night  use  of  water  fall- 
ing always  upon  the  same  individuals,  the  rotation  period  may 


Measurement   of   Water 


243 


be  made  to  include  a  fraction  of  a  day,  say  8%  days  instead  of 
8,  as  in  the  one  cited;  or,  after  a  certain  number  of  rotations, 
the  water  may  be  given  first  to  a  different  member  in  the 
circuit,  and  thus  change  the  time  of  day  at  which  each  gets 
his  turn. 

In  those  cases  where  the  supply  of  water  in  the  ditch  is 
always  the  same,  this  is  the  most  accurate  and  best  method  of 
dividing  water  which  has  been  devised,  and  where  the  amount 
of  water  which  the  ditch  carries  is  known,  it  gives  every  one  a 
definite  knowledge  of  the  amount  of  water  he  is  using. 

It  often  happens,  however,  that  the  volume  of  water  changes 
from  time  to  time,  and  when  this  is  true  those  who  chance  to 
be  using  water  when  the  supply  is  high  will  receive  most. 
But  if  the  period  of  rotation  is  short,  the  injustice  will  seldom 
be  very  great,  and  where  the  periods  of  rotation  are  short,  the 
service  is  usually  more  convenient  and  better  for  other  reasons 
than  that  of  a  more  equitable  division  of  the  water,  because  it 
permits  a  user  to  apply  his  water  to  certain  fields  one  date  and 
to  another  on  his  next  turn,  thus  permitting  him  to  do  his  fit- 
ting and  cultivation  between  irrigations  to  a  greater  advantage. 


The    Subdivision   of  Laterals 


too   much  water  to   be   used  to 


IT 


\7 


Where  the  lateral  carries 
advantage  by  single  indi- 
viduals, this  may  be  sub- 
divided readily  into  two 
exactly  equal  portions,  and 
these  two  divisions  may 
be  again  subdivided  into 
two  precisely  equal  streams. 
But  in  order  that  the  di- 
vision  may  be  exact,,  it 
must  be  done  in  certain 
ways,  as  represented  in  Fig.  43.  If  the  two  branches  of  the  lateral 
form  equal  angles  with  the  main,  have  the  same  fall,  and  their 
bottoms  at  the  same  level  where  they  start,  they  will  carry  equal 


_  . 

Pig.  43.    Branching  of  canal  to  divide  "water 

equally  U  and  5)  and  unequally  (  (7). 


244  Irrigation    and    Drainage 

volumes  of  water  if  their  dimensions  are  exactly  the  same  as 
shown  at  A  and  B.  But  if  the  division  is  made  as  at  C,  or  in 
any  other  manner,  which  makes  the  two  arms  in  any  way 
unlike,  one  will  carry  more  water  than  the  other.  So,  too,  if 
care  is  not  taken  to  keep  the  main  and  the  two  branches  clean 
where  the  division  is  made,  it  will  not  be  exact. 

When  an  effort  is  made  to  divide  the  main  into  two  unequal 
parts,  or  into  an  odd  number  of  equal  parts,  the  task  becomes 
an  extremely  difficult  one,  and  one  which  is  not  likely  to  be 
accomplished,  and  the  attempt  should  be  avoided. 

The  cause  of  the  difficulty  is  found  in  the  fact  that  the  water 
travels  with  the  greatest  velocity  in  the  center  of  the  stream 
and  diminishes  in  speed  as  the  sides  are  approached,  so  that  if 
the  main  is  divided  into  two  branches  which  have  cross -sections 
in  the  ratio  of  1  to  2,  the  larger  arm  will  carry  more  than  twice 
the  amount  of  the  smaller  one,  because  it  must  take  a  larger 
share  of  the  water  moving  in  the  central  portion  of  the  main. 
Or  if  the  main  is  divided  into  three  equal  laterals,  then  the 
central  branch  is  sure  to  carry  more  water  than  either  of  the 
two  taking  the  water  from  nearer  the  sides,  and  it  is  not  prac- 
ticable to  so  adjust  the  dimensions  of  these  branches  that  with 
varying  volumes  of  water  moving  in  the  main  the  desired  ratios 
shall  always  be  secured  in  the  divisions. 

The    Use  of  Divisors 

When  it  is  desired  to  remove  from  a  ditch  a  certain  portion 
of  the  amount  of  water  which  it  is  carrying,  this  is  sometimes 
attempted  by  means  of  an  arrangement  represented  in  Fig.  44, 
called  a  divisor,  in  which  the  portion  A  is  set  into  the  channel 
some  fractional  part  of  the  whole  width,  determined  by  the 
amount  which  it  is  desired  to  take  out.  Thus,  if  it  was  desired 
to  take  out  one -fifth  of  the  stream,  and  the  lateral  had  a  width 
of  40  inches,  the  divisor  would  be  set  in  toward  the  center  8 
inches.  But  from  what  has  already  been  said,  it  follows  that 
less  than  one-fifth  of  the  water  can  thus  be  removed,  for  the 
two  reasons,  that  the  section  of  the  stream  removed  does  not 


Division   of    Water  245 

have  the  mean  velocity  of  the  part  remaining,  and,  having  to 
change  its  direction  to  one  at  right  angles,  its  velocity  is  still 
further  checked  in  making  the  turn.  The  smallest  users  of  water 

by  this    system,    therefore,  in-     

variably  receive  an  amount 
which  is  less  than  they  are 
entitled  to  use,  while  the  larger 
users  receive  more.  In  order 
to  reduce  this  inequality  of 
division,  the  practice  of  insert- 
ing a  weir-board  in  the  canal 
just  above  the  divisor,  so  as  to  Fig"  "'  °ne  form  of  water  divi80r- 
restore  a  more  nearly  equal  velocity  across  the  stream,  is  some- 
times adopted ;  and  if  the  canal  is  broadened  above  the  measur- 
ing-box, so  that  the  water  approaches  the  weir  slowly  and  passes 
over  it  smoothly  without  contraction,  Carpenter  states  that  the 
method  will  give  as  satisfactory  results  as  any  with  which  he 
is  acquainted. 

The    Use  of  Modules 

A  module  is  denned  as  a  means  of  taking  out  of  a  canal  a 
definitely  specified  quantity  of  water,  measured  as  so  many  inches, 
cubic  feet  per  second,  or  other  units,  rather  than  the  simple 
division  of  a  stream  into  a  certain  number  of  parts,  as  is  the 
case  where  the  divisor  is  used. 

Two  types  of  modules  are  employed,  one  based  upon  the 
principle  of  the  weir  as  a  means  for  measuring  water,  and  the 
other  on  the  laws  governing  the  flow  of  water  through  orifices. 
If  it  were  readily  practicable  to  establish  and  maintain  any 
desired  pressure  at  a  weir  or  an  opening,  water  could  be  appor- 
tioned for  irrigation  with  satisfactory  precision  with  the  aid  of 
modules,  but  no  method  for  doing  this  has  yet  been  devised, 
although  much  study  through  many  centuries  has  been  devoted 
to  it. 

The  spill-box,  invented  by  A.  D.  Foote,  and  represented  in 
Fig.  45,  is,  perhaps,  as  satisfactory  a  means  for  maintaining  a 


246 


Irrigation   and    Drainage 


nearly  uniform  head  against  either  a  weir  or  an  opening  as  has 
yet  been  devised.  Its  essential  feature  is  a  long,  sharp  lip, 
over  which  the  water  may  spill  back  into  the  canal  in  a  thin 
sheet,  and  thus  maintain  a  nearly  constant  pressure  back  of 


Fig.  45.     Spill-back  method  of  dividing  water. 

the  lip  of  a  weir  or  above  an  opening.  But  this  arrangement 
does  not  and  cannot  maintain  a  constant  pressure  where  there 
is  any  considerable  fluctuation  in  the  volume  of  water  in  the 
main  canal;  and,  since  the  depth  of  water  above  the  opening 
or  lip  of  the  weir  must  always  be  small,  even  a  slight  change 


Division   of   Water  247 

in  the  depth  of  the  water  over  the    lip  of  the  spill -back  must 
make  a  perceptible  difference  in  the  discharge. 

Further  than  this,  where  the  form  of  the  opening  is  designed 
to  be  made  longer  or  shorter  by  means  of  a  sliding  valve  accord- 
ing as  more  or  less  water  is  desired,  the  amount  discharged, 
even  when  the  head  is  maintained  rigidly  constant,  is  not 
directly  proportional  to  the  length  of  the  opening,  because  the 
number  of  inches  of  margin  upon  which  the  resistance  to  flow 
depends  does  not  maintain  a  constant  ratio  to  the  cross -section 
of  the  opening.  The  more  margin  there  is  in  proportion  to  the 
area  of  the  opening,  the  greater  must  be  the  loss  of  discharge 
through  friction  and  contraction,  so  that  the  most  exact  and 
generally  satisfactory  way  of  apportioning  water  among  users 
which  has  yet  been  devised,  is  that  of  bisecting  the  stream  until 
its  volume  has  become  suitable  for  individual  use,  and  then  sub- 
dividing by  time  under  some  system  of  rotation. 


CHAPTER   VII 

THE    CHARACTER    OF   WATER   FOR   IRRIGATION 

THE  characteristics  which  determine  the  suitability 
of  water  for  the  purposes  of  irrigation  must  depend 
upon  the  chief  objects  for  which  the  water  is  used  : 
whether  it  is  to  control  temperature,  as  in  the  case  of 
winter -meadows  and  in  cranberry  culture  ;  to  supply 
plant-food,  as  in  the  case  of  summer  water-meadows ; 
to  meet  the  simple  need  of  water  for  the  transpiration 
of  the  growing  crop,  or  to  deposit  sediments  for  the 
purpose  of  building  up  the  surface  of  low- lying  areas, 
as  in  the  case  of  warping. 

TEMPERATURE     OF    WATER    FOR     IRRIGATION 

Where  one  of  the  prime  objects  in  the  use  of  water 
for  irrigation  is  to  stimulate  plant -growth,  the  warmer 
the  water  is  within  the  natural  ranges  of  .temperature 
the  better  are  the  results.  According  to  Ebermayer, 
when  the  temperature  of  the  soil  in  which  a  crop  is 
growing  has  been  lowered  to  from  45°  to  48°  F.,  phys- 
iological processes  are  brought  nearly  to  a  standstill 
in  it,  and  the  maximum  rate  of  growth  does  not  be- 
come possible  until  after  the  soil  temperature  has 
risen  above  68°  to  70°.  It  is  plain,  therefore,  that  if 
large  volumes  of  cold  water  were  applied  to  the  soil  at 

(248) 


Temperature  of  Water  for  Irrigation          249 

one  time,  and  especially  if  a  flooding  system  were 
adopted  by  which  the  cold  water  were  kept  moving 
over  the  ground  in  the  growing  season  during  several 
days,  the  temperature  of  the  soil  might  easily  be 
brought  so  low  as  to  seriously  interfere  with  normal 
growth. 

The  dangers,  however,  from  using  cold  irrigation 
waters  are  not  as  great  as  might  at  first  be  supposed; 
and  it  is  seldom,  where  good  judgment  is  exercised,  that 
the  low  temperature  of  the  water  of  wells  and  springs 
need  prohibit  its  use  for  the  purposes  of  irrigation. 

In  the  first  place,  there  are  few  cases  where  the 
temperature  of  well  or  spring  water  during  the  irri- 
gation season  will  be  found  as  cold  as  45°  F.,  the 
more  usual  temperature  being  nearly  50°  or  above. 
In  the  second  place,  water  warms  very  rapidly  during 
bright  summer  days,  when  spread  over  the  surface 
of  the  ground,  or  when  led  along  furrows,  and  even 
wh'ile  flowing  through  ditches,  for  it  absorbs  the  direct 
heat  from  the  sun  readily,  as  the  rays  of  light  pene- 
trate it,  and  is  further  indirectly  warmed  by  the 
balance  of  the  sunshine  which,  passing  through  the 
water,  is  arrested  by  the  dark  soil  beneath.  While 
the  water  is  flowing  over  the  surface  of  the  ground, 
if  its  temperature  is  below  that  of  the  soil,  it  really 
stores  much  heat  which  otherwise  would  be  lost,  be- 
cause relatively  much  less  will  be  lost  by  radiation 
from  the  hot  surface  of  the  soil  and  stored  in  the 
water,  leaving  less  to  pass  away  from  the  dry  ground 
whose  immediate  surface  becomes  very  warm,  and 
hence  fitted  to  lose  heat  rapidly. 


250  Irrigation    and    Drainage 

In  the  third  place,  the  temperature  of  the  surface 
foot  of  soil  in  the  daytime  of  midsummer,  with  its 
contained  moisture,  is  usually  as  high  as  68°  to 
75°,  and  to  lower  its  temperature  1°  F.  requires  the 
absorption  by  water  added  of  from  25  to  40  heat  units, 
according  as  the  soil  varies  from  a  nearly  pure  sand, 
weighing  110  pounds  per  cubic  foot,  and  containing 
4  per  cent  of  water,  to  a  humus  soil,  containing  30 
per  cent  of  water  and  50  pounds  of  dry  matter  per 
cubic  foot. 

One  heat  unit  is  taken  as  the  amount  needed  to  raise  1 
pound  of  water  at  32°  to  33°  F.  With  the  relations  stated,  it 
appears  that  4  inches  of  water  having  a  temperature  of  45°  F. 
applied  to  a  field  having  a  soil  temperature  of  75°  might  lower 
the  surface  foot  to  65°  or  61.7°,  according  to  the  specific  heat  of 
the  soil  ;  and  with  a  soil  temperature  of  68°,  the  lowest  tem- 
perature the  4  inches  of  water  could  produce  would  range  be- 
tween 60°  and  57.6°.  But  this  assumes  that  the  water  is  applied 
at  once,  with  no  opportunity  for  warming  until  it  is  brought  into 
contact  with  the  soil,  which,  of  course,  cannot  be  the  case.  If 
the  irrigation  water  has  a  temperature  of  50°  F.,  then  the  lowest 
degree  4  inches  of  water  could  force  upon  the  surface  foot  of 
soil  would  be  some  amount  above  66.7°  to  63.7°  when  the  origi- 
nal soil  temperature  was  75°,  or  62°  to  59.9°  if  the  initial  soil 
temperature  were  68°  F. 

The  results  summarized  on  page  214  indicate  that  the  mean 
amount  of  water  used  in  single  irrigations  is  at  the  rate  of  2.02 
inches  once  in  10  days.  Hence,  were  the  coldest  water  used  in 
this  quantity,  the  greatest  depression  of  the  temperature  of  the 
surface  foot  could  not  exceed  6.7°  F.  This  assumes  that  neither 
the  water  nor  the  soil  receives  any  heat  during  the  time  the 
water  is  being  applied.  It  is  clear,  therefore,  that  where  good 
judgment  is  exercised  in  the  application  of  either  well  or  spring 
water,  it  may  be  used  without  in  any  serious  way  interfering  with 
normal  growth.  The  chief  danger  will,  of  course,  lie  in  the  ap- 


Fertilizing   Value  of  Water  251 

plication  of  excessive  amounts  of  water,  when  injury  would  fol- 
low certainly,  and  sooner  than  where  warmer  water  is  at  hand. 

Warm  water  is  better  than  cold,  and  in  making  a  choice  of 
waters  it  is,  of  course,  best  to  select  the  warmest  where  this  can 
be  done.  But  the  point  we  wish  to  emphasize  is,  that  well  and 
spring  water  and  mountain  streams  may  be  used  to  advantage 
for  irrigation  where  warmer  water  is  not  at  hand.  Mr.  Crane- 
field*  has  experimented  with  tomatoes,  radishes  and  beans  grown 
in  a  greenhouse  and  in  the  garden,  irrigated  with  water  at  32°, 
and  has  found  them  to  do  nearly  as  well  as  those  given  water  at 
70°  or  100°. 

The  writer  waters  his  own  garden  and  lawn  directly  from  a 
well  with  water  having  a  temperature  of  48°  to  50°  F.,  and  the 
present  year  we  cut  with  a  lawn  mower,  on  21,869  square  feet 
of  lawn  about  the  house,  between  May  6  and  November  5,  enough 
grass  to  feed  one  cow  all  she  needed  for  95%  days.  On  90,709 
square  feet,  including  the  lawn,  or  2.08  acres,  we  this  year  fed, 
by  soiling,  two  cows  and  one  horse  from  May  6  until  November 
5,  and  put  into  the  barn  besides  4.75  tons  of  hay,  .14  acres  of 
this  ground  being  in  Stowell's  Evergreen  sweet  corn.  Three  crops 
of  clover  were  cut  from  the  same  ground,  and  the  third  cutting, 
November  1,  averaged  a  ton  of  hay  per  acre,  and  was  a  little 
past  full  bloom,  and  yet  the  watering  was  done  directly  from 
the  well  with  water  at  48°  F. 

FERTILIZING    VALUE    OF    IRRIGATION    WATER 

In  traveling  from  place  to  place  in  Europe,  it  was 
a  continual  surprise  to  the  writer  to  learn  from  those 
who  were  using  water  for  the  irrigation  of  meadows 
that  the  fertility  which  the  river  waters  added  to  the 
soil  was  generally  regarded  as  the  chief  advantage 
derived  from  them.  The  vast  volumes  of  water  which 
are  sometimes  used  for  this  purpose  have  already  been 
cited. 


*Fifteenth  Ann.  Kept.  Wis.  Agr.  Exp.  Station,  p.  250. 


252  Irrigation   and    Drainage 

As  an  example  of  the  amount  and  kind  of  material 
which  would  be  added  to  the  land  where  what  is  re- 
garded as  exceptionally  pure  water  is  used,  we  com- 
pute from  the  results  of  analyses  of  the  water  of  the 
Delaware  river*  the  amount  of  material  contained  in 
solution  in  24  acre -inches,  as  follows: 

Materials  in  %4  acre-inches  of  Delaware  river  ivater 

Pounds 

Calcium  carbonate 242.6 

Magnesium  carbonate 166.16 

Potassium  carbonate 31.74 

Sodium  chloride 20.54 

Potassium  chloride . 1 .86 

Calcium  sulphate 35.48 

Calcium  'phosphate 26.14 

Silica 93.34 

Ferric  oxide 56 

Organic  matter  containing  ammonia  ....     117.62 


Total 741.08 

The  average  amounts  of  nitrogen  compounds,  as 
computed  from  the  chemical  analyses  of  the  waters  of 
twelve  streams  in  New  Jersey,  are  as  follows: 

Nitrogen  Compounds  dissolved  in  24  acre-inches  of  water  from  12 
streams  in  New  Jersey 

Pounds 

Free  ammonia 15.63 

Albuminoid  ammonia  .  f 81.12 

Nitrates 772.67 

Nitrites  .86 


Total 870.28 


*Rept.  New  Jersey  Geol.  Survey  1868,  p.  102. 


Sewage   Waters  for   Irrigation  253 

Using  the  figures  of  T.  M.  Read*  regarding  the 
amount  of  materials  which  the  great  rivers  of  the 
world  bear  in  solution  to  the  sea,  it  appears  that  the 
Mississippi  and  St.  Lawrence  rivers,  in  North  America, 
and  the  Amazon  and  La  Plata,  in  South  America, 
carry  an  amount  such  that  the  average  is  655.6  pounds 
per  each  24  acre-inches  of  water. 

Goss  and  Haret,  from  analyses  of  the  water  of  the 
Rio  Grande  at  different  periods  from  June  1  to  Octo- 
ber 31,  compute  that  24  acre-inches  of  the  water 
contained  in  sediment  and  in  solution  1,075  pounds 
of  potash,  116  pounds  of  phosphoric  acid,  and  107 
pounds  of  nitrogen.  The  water  of  this  river  contains 
a  sufficient  amount  of  sediment  so  that  24  acre- inches 
of  it  furnishes  81,309  pounds,  or  more  than  4  tons 
per  acre. 

It  is  evident  from  these  data  that  the  ordinary 
clear  waters  of  rivers,  lakes,  springs  and  wells  cannot 
be  expected  to  bear  to  the  fields  upon  which  they  are 
applied  a  sufficient  amount  of  plant -food  to  meet  the 
needs  of  crops,  unless  the  water  is  applied  in  much 
larger  volumes  than  is  required  to  meet  the  demands 
of  soil  moisture. 

SEWAGE    WATERS    FOR    PURPOSES    OF    IRRIGATION 

It  may  be  laid  down  as  a  general  rule  that  the 
water  of  highest  value  for  the  purposes  of  irrigation 
is  the  sewage  of  large  cities,  unless  it  contains  too 

*Am.  Jour.  Sci.,  vol.  xxix.,  p.  290. 
tNew  Mexico  Expt.  Sta.,  Bull.  12. 


254  Irrigation    and    Drainage 

large   amounts   of    poisonous   products   from   factories 
in  the  form  of  injurious  chemical  compounds. 

The  organic  matter  of  sewage,  in  both  its  soluble 
and  finely  divided,  suspended  form  of  solids,  when 
sufficiently  diluted  with  other  water,  is  of  the  highest 
value  as  a  fertilizer  for  many  crops,  and  in  all 
warm  climates  it  is  often  practicable  and  very  de- 
sirable to  use  such  water  for  this  purpose. 

Reference  has  already  been  made  to  the  use  of 
sewage  waters  from  the  city  of  Milan  on  the  water- 
meadows  of  Italy.  The  far-famed  Craigentinny 
meadows,  outside  of  Edinburgh,  are  another  emphatic 
illustration  of  the  value  of  sewage  in  the  production 
of  grass,  and  Storer,  after  visiting  them  in  1877, 
writes  as  follows: 

"In  1877  there  were  400  acres  of  these  '  forced 
meadows  *  near  Edinburgh,  and  they  are  said  to  in- 
crease gradually.  The  Craigentinny  meadows,  just 
now  mentioned,  were  about  200  acres  in  extent,  and 
they  had  then  been  irrigated  30  years  and  more. 
They  were  laid  down  at  first  to  Italian  ray  grass 
and  a  mixture  of  other  grass  seed,  but  these  arti- 
ficial grasses  disappeared  long  ago,  couch-grass  and 
various  natural  grasses  having  taken  their  place. 
The  grass  is  sold  green  to  cow -keepers,  and  yields 
from  $80  to  $150  per  acre.  One  year  the  price 
reached  $220  per  acre.  They  get  five  cuts  between 
the  1st  of  April  and  the  end  of  October.  This  farm 
of  200  acres  turns  in  to  its  owner  every  year  $15,000 
to  $20,000  at  the  least  calculation,  and  his  running 
expenses  consist  in  the  wages  of  'two  men,  who  keep 


Sewage   Waters  for  Irrigation 


255 


the  ditches  in  order.  The  sewage  he  gets  free.  The 
yield  of  grass  is  estimated  at  from  50  to  70  tons 
per  acre." 

In  1895,  18  years  later,  the  writer  visited  the 
meadows  described  above,  and  Figs.  46  and  4Y  were 
taken  at  the  time.  The  first  figure  shows  a  load 
of  grass,  estimated  to  weigh  2,500  pounds,  cut  to 
feed  23  cows  during  one  day,  from  an  area  of  2,734 
square  feet.  Seven  acres  of  this  grass  had  been 
purchased  to  feed  the  herd  of  23  cows  from  May  1  to 


Fig.  4G.     Two  thousand  five  hundred  pounds  of  grass  cut  on  2,734  sq.  ft. 
of  Craigentinny  Meadows,  Edinburgh,  Scotland. 

October  20,  during  which  time  the  grass  would  be 
cut  four  or  five  times,  and  the  price  paid  for  this 
grass,  sold  at  auction,  varied  from  $77.44  to  $111.32 
per  acre,  according  to  the  quality  of  the  several  plots 
making  up  the  seven  acres  purchased.  The  increase  of 
these  meadows  about  Edinburgh,  it  was  said,  was 
tending  to  lower  the  price  which  this  grass  could 


•256  Irrigation    and    Drainage 

command,  but  the  superintendent  informed  me  that 
during  the  past  twenty  years  the  average  price  per 
acre  for  the  whole  estate  had  been  $102.20.  Yet 
this  grass  is  cut  by  the  purchasers  and  hauled  three 


Fig.  47.    Distribution  of  sewage  on  Craigentinny  meadows,  Edinburgh, 
Scotland,  just  after  ctitting  grass. 

to  four  miles  day  by  day  to  feed  their  cows,  stabled 
and  milked  in  the  crowded  business  portions  of 
the  city. 

When  it  is  further  stated  that  much  of  the  land 
upon  which  this  grass  is  now  grown,  and  has  been 
continuously  grown  for  nearly  a  century  without 
rotation,  was  originally  a  waste  sandy  sea  beach,  it 
will  be  the  better  appreciated  how  valuable  is  such 
sewage  water  for  the  purposes  of  irrigation. 

Regarding  the  healthfulness  of  milk  produced  from  grass 
grown  under  sewage  irrigation,  statements  like  the  following 
are  repeatedly  being  made  :  "The  only  question  is,  whether 
there  may  not  remain  adhering  to  grass  which  has  been  bather) 


Sewage    Water  for  Irrigation  257 

with  sewage  some  germs  of  typhoid,  cholera  or  other  vile  disease 
which  are  propagated  in  human  excrement;"  and  in  view  of 
what  is  now  known  regarding  the  nature  of  such  diseases,  it 
is  not  strange  that  such  fears  should  arise  in  the  minds  of 
sanitarians. 

But  in  view  of  the  fact  that  milk  has  been  produced  from 
such  feed  for  nearly  a  century  immediately  within  the  city  of 
Edinburgh,  the  sewaged  grass  traversing  the  streets  daily  during 
the  whole  season  in  sufficient  quantity  for  several  thousand  cows, 
and  the  milk  so  produced  wholly  consumed  by  its  people  with- 
out protest,  must  be  taken  as  the  safest  possible  evidence 
that  there  is  practically  little  danger  in  this  direction  ;  and 
when  it  is  remembered  that  the  large  city  of  Milan,  Italy,  has 
been  supplied  with  milk  produced  from  such  grass  fed  the  year 
round  for  more  than  two  centuries,  the  evidence  against  the 
fear  expressed  is  more  than  doubly  strong,  coming,  as  it  does, 
from  a  warm  southern  climate  and  covering  so  long  a  period. 

The  question,  however,  is  still  discussed,  and  in  order  that 
there  may  be  no  tendency  to  throw  public  vigilance  off  its  guard 
in  so  grave  a  matter,  we  quote  from  the  Edinburgh  Evening 
Dispatch  of  July  5,  1895,  parts  of  a  discussion  which  was  being 
had  at  the  time  of  my  visit,  as  follows: 

"  Last  week  we  called  attention  to  the  peculiar  tactics 
adopted  by  some  medical  gentlemen,  sanitarians  and  others,  who 
are  attempting  to  float  a  new  dairy  company.  *  *  *  One  of 
the  strategic  movements  of  these  <  philanthropic '  speculators  was 
to  try  and  create  a  prejudice  against  the  milk  produced  in  the 
Edinburgh  dairies,  on  the  ground  that  the  cows  were  largely 
fed  on  sewage  grass  during  the  summer.  In  regard  to  this,  we 
pointed  out  that  the  royal  commission  which  investigated  the 
whole  subject  of  sewage  farming  some  years  ago,  reported  that 
they  had  failed  to  discover  a  single  case  where  injury  to  health 
had  resulted  from  the  use  of  milk  drawn  from  cows  fed  on 
sewage  grass.  Singe  our  article  on  the  subject  appeared  last 
week,  our  attention  has  been  called  to  some  further  evidence 
which  fully  confirms  the  conclusions  at  which  the  royal  com- 
missioners htfft  arrived.  In  his  evidence  given  before  the  Rivers 


258  Irrigation    and    Drainage 

Pollution  Commissioners,  the  medical  officer  of  health  for  Edin- 
burgh, Dr.  Littlejohn,  now   Sir  Henry  Littlejohn,  said: 

«  <  The  cows  in  Edinburgh  are  chiefly  fed  with  sewage  grass 
that  is  grown  on  Craigentinny  meadows.  I  have  thought  that 
there  might  be  objection  to  feeding  cows  upon  grass  so  grown, 
because  I  was  of  opinion  that  grass  so  grown  might  be  of  inferior 
quality.  But  practically  I  have  failed  to  detect  any  bad  effects 
resulting  from  the  use  of  such  grass.' 

"Another  point  which  these  philanthropic  sanitarians  tried  to 
make  out  against  milk  from  sewage-grass-fed  cows  was  that 
such  milk  'turned  putrid  in  a  very  short  space  of  time.'  The 
most  ample  evidence  is  forthcoming  to  show  the  absolute  ground- 
lessness of  this  contention  also.  Mr.  Spier,  the  Scottish  Dairy 
Commissioner,  who  has  conducted  most  of  the  dairy  experiments 
which  have  been  carried  on  for  the  Highland  Agricultural 
Society,  has  fully  tested  the  matter,  and  he  writes  to  us  as 
follows  on  the  subject: 

"  <  By  way  of  testing  this  point,  I  set  aside  eighteen  cows  for 
the  experiment:  Of  these,  six  were  fed  in  the  house  on  sewage, 
grass,  six  were  fed  in  the  house  on  vetches,  and  the  other  six 
were  pastured  in  the  fields.  Milk  from  each  of  these  sets  of 
cows  w^as  repeatedly  set  aside  in  separate  vessels  until  it  became 
decidedly  tainted,  and  out  of  the  numerous  tests  the  milk  from 
the  cows  fed  on  sewage  grass  never  once  turned  sour  first.  In 
the  majority  of  cases,  the  milk  from  the  cows  fed  on  the  vetches 
was  the  first  to  turn  sour,  while  the  milk  from  the  sewage  grass 
and  on  the  pasture  was  about  equal  in  keeping  properties.  On 
several  occasions  the  milk  from  the  three  lots  of  cows  was  kept 
for  the  same  length  of  time  and  churned  separately,  but  on  no 
single  occasion  did  the  butter  from  the  cows  fed  on  sewage  grass 
become  rancid  before  the  other  lots  did.  Samples  of  the  butter 
from  the  three  different  lots  of  milk  were  sent  to  the  chemist 
of  the  society,  and  he  was  unable  to  tell  which  was  which. ' " 

These  statements  will  serve  to  call  attention  to  the  fears 
which  have  been  expressed  on  theoretical  considerations,  and 
the  nature  of  the  evidence  which  appears  to  indicate  that  there 
is  little  ground  for  them. 


Value  of  Turbid    Water  259 

THE    VALUE    OF    TURBID    WATER    IN     IRRIGATION 

Next  in  value  to  warm  sewage  water  for  irrigation 
must  be  placed  that  of  streams  carrying  considerable 
quantities  of  suspended  solids.  It  is  generally  recog- 
nized that  the  richest  and  most  enduring  soils  of  the 
world  are  those  formed  from  the  alluvium  of  streams 
laid  down  by  the  water  on  its  flood  plains,  and 
reworked  many  times  over  as  the  stream  shifts  its 
course  from  side  to  side  in  the  valley;  and  when  this 
is  true,  it  will  not  be  strange  that  the  water  of  turbid 
streams  has  generally  been  held  in  great  esteem  for 
irrigation,  on  account  of  its  high  fertilizing  value. 

In  the  case  of  the  Rio  Grande  river,  Goss  has 
shown  that  the  application  of  24  inches  of  this  water 
would  add  nearly  one -quarter  of  an  inch  of  soil  to 
the  field  in  the  form  of  river  sediment,  and  that  this 
sediment  would  contain  per  acre  1,821  pounds  of 
potassium  sulphate,  116  pounds  of  phosphoric  acid 
(P2O5),  and  107  pounds  of  nitrogen.  Four  years  of 
irrigation  at  this  rate  would  add  an  inch  of  soil  to 
the  field,  and  24  years  would  cover  it  6  inches  deep 
with  a  sediment  containing  three  times  the  amount 
of  potash  found  in  the  average  clay  soil,  and  the  same 
percentage  of  phosphoric  acid  and  a  high  percentage 
of  nitrogen. 

When  such  sediments  are  laid  down  upon  coarse, 
sandy  soils,  it  will  be  readily  appreciated  that  the 
gain  to  the  field  is  far  greater  than  that  due  to  the 
mere  plant -food  which  the  sediments  contain;  for  such 
sediments,  being  composed  of  very  fine  grains,  their 


260  Irrigation   and    Drainage 

influence  in  improving  the  texture  of  the  soil  is  quite 
as  great  as  that  due  to  the  fertilizers  contained. 

The  sediment  carried  by  the  Po  is  given  by  Lom- 
bardini  as  TOTT  of  the  volume  of  the  river,  and  on 
this  account  the  waters  are  held  in  high  esteem  for 
irrigation. 

The  river  Nile,  during  the  time  of  the  rainy  season 
of  mountainous  Abyssinia,  comes  loaded  with  sedi- 
ment constituting  BTT  of  the  volume  of  the  water; 
and  this,  under  the  old  system  of  the  Pharoahs  of 
basin  irrigation,  which  permitted  the  rich  mud  to  col- 
lect on  the  fields,  kept  them  fertile  for  thousands  of 
years,  and  they  are  so  today;  whereas  in  Lower  Egypt, 
where  the  old  practice  has  been  abandoned  in  recent 
years  for  an  "improved"  system,  which  does  not  per- 
mit the  utilization  of  the  rich  Nile  mud,  the  fields  are 
fast  deteriorating  in  fertility,  although  only  half  a 
century  has  passed. 

The  Durance,  in  France,  is  famous  for  its  fertile 
waters,  and  they  carry  at  the  ordinary  maximum  A  of 
their  weight  of  sediment,  or  nearly  1.9  pounds  per 
cubic  foot,  equal  to  82,464  pounds  per  each  acre-foot 
of  water.  In  rare  cases  the  sediment  of  this  stream 
rises  to  iV  of  the  water  by  weight,  and  the  average 
proportion  for  nine  years  has  been  found  to  be  Tic". 
When  such  waters  are  used  year  after  year  on  poor 
lands,  the  improvement  becomes  very  great,  while  on 
the  better  lands  a  high  and  permanent  degree  of  fer- 
tility is  maintained  indefinitely,  with  heavy  yields  per 
acre  as  the  result. 


Improvement   of  Land   by    Silting  261 

IMPROVEMENT    OF    LAND    BY    SILTING 

Nature's  method  of  depositing  the  fine  silt  borne 
along  by  streams,  whenever  they  overflowed  their 
banks,  early  suggested  the  idea  of  directing  this  work 
so  that  the  materials  should  be  laid  down  on  sandy 
or  gravelly  soils,  to  so  improve  the  texture  and  fer- 
tility as  to  convert  comparatively  worthless  areas  into 
extremely  productive  lands. 

In  other  cases,  where  marshy,  low -lying  lands,  or 
shallow  lakes  and  estuaries  were  lying  adjacent  to 
turbid  streams,  the  waters  have  been  so  turned  upon 
them  and  then  led  away  as  to  lay  down  mantles  of 
rich  soil  of  sufficient  thickness  to  raise  the  surface  to 
such  a  height  as  to  permit  of  drainage,  and  thus 
reclaim  worthless  swamps,  converting  them  into  rich, 
arable  fields. 

In  England,  where  the  method  was  introduced 
from  Italy  to  reclaim  waste  lands  near  the  sea,  the 
process  is  called  "warping,"  and  in  France  "colmatage." 
In  England,  as  on  the  Humber,  where  the  tides  rise 
several  feet,  and  the  waters  of  the  river  are  turbid, 
much  land  has  been  reclaimed  by  warping.  Centuries 
ago  low,  flat  lands  were  dyked  off  from  the  sea  to 
prevent  inundation;  but  in  more  recent  years,  to 
this  improvement  was  added  the  one  under  considera- 
tion. Tide  sluices,  provided  with  gates  to  admit 
the  turbid  water  held  back  by  the  sea,  were  set  in 
the  dykes,  and  the  low  lands  were  laid  out  in  fields 
surrounded  by  banks  for  retaining  the  water  until 
the  sediment  borne  in  upon  the  area  should  have  time 


262  Irrigation   and    Drainage 

to  settle,  when  the  clear  water  returned  to  the  stream 
with  the  fall  of  the  tide. 

So  large  was  the  amount  of  sediment  carried  in 
the  water,  and  so  rapid  was  the  silting- up,  that  fields 
of  10  to  15  acres  are  said  to  have  been  raised  from 
one  to  three  feet  during  a  single  season,  thus  convert- 
ing worthless  peat  bogs  in  so  brief  a  time  into  fields 
of  the  richest  soil.  One  season  spent  in  warping, 
one  for  the  ground  to  settle  and  become  compacted, 
and  a  third  to  get  it  into  grass,  is  the  usual  time 
required  for  reclamation,  and  after  this  such  fields 
produce  enormous  crops  of  almost  any  kind  suited  to 
the  climate.  In  other  regions,  where  less  sediment 
is  carried  in  the  water,  or  where  greater  depths  of 
silt  must  be  laid  down  in  order  to  secure  the  desired 
level  of  the  surface,  longer  time  is  required  for  the 
work,  but  in  Italy  fields  have  been  raised  as  much 
as  6  to  7  feet  in  10  years. 

In  other  portions  of  the  world,  notably  in  the 
Nile  valley,  a  modification  of  this  system  of  silting 
for  the  yearly  enrichment  of  the  soil  is  practiced. 
To  this  end  the  ancient  irrigators,  both  in  upper  and 
lower  Egypt,  had  laid  out  the  accessible  lands  for 
basin  irrigation,  by  which  the  turbid  and  fertile  waters 
of  the  Nile,  at  its  flood  season,  could  be  led  upon  the 
settling  areas  and  held  until  the  rich  sediments  were 
laid  down,  thus  converting  otherwise  comparatively 
worthless  sandy  soils  into  the  richest  and  most  de- 
sirable of  fields,  and  so  maintained  for  thousands  of 
years  by  periodic  inundations. 

Then,  again,  in   France,  as   in   the   Moselle  valley, 


Improvement   of  Land   by    Silting  263 

and  in  the  district  of  the  mouths  of  the  Rhone, 
between  Aries  and  Mirimas,  for  example,  on  broad, 
flat  plains  of  extremely  coarse  gravel,  where  in  earlier 
years  the  uncontrolled  waters  have  permitted  no  soil 
to  form,  this  system  of  silting,  "colmatage"  or 


Fig.  48.    Head-gate  on  the  Durance  above  Avignon,  France. 

"warping,"  has  been  introduced,  and  rich  deposits 
laid  down  among  and  above  the  coarse  materials, 
until  productive  fields,  orchards  and  gardens  have 
taken  the  place  of  wide  reaches  of  naked  gravel 
beds. 

Fig.  48  is  a  head  -  gate  on  the  Durance,  above 
Avignon,  where  a  portion  of  the  water  of  the  district 
is  taken  out.  The  soil  here,  for  depths  exceeding 
10  feet,  as  shown  by  cuts  observed,  is  made  up,  seem- 


264  Irrigation  and   Drainage 

ingly,  of  70  per  cent  of  coarse  gravel  from  %inch 
up  to  4  and  5  inches  in  diameter,  and  a  surprisingly 
large  per  cent  is  composed  of  the  larger  sizes.  Among 
this  gravel  the  river  silt  has  been  deposited  until 
fields  of  alfalfa  and  wheat,  as  well  as  gardens  and 
almond  orchards,  are  grown  upon  these  extremely 
pervious  beds. 

OPPORTUNITIES    FOR     SILTING    IN    EASTERN 
UNITED     STATES 

East  of  the  Mississippi,  extending  from  Wiscon- 
sin through  Michigan,  New  York,  and  into  New 
Jersey,  as  well  as  in  New  England,  there  are  exten- 
sive areas  of  very  sandy  lands  which,  if  they  were 
subjected  to  this  process  of  silting,  so  as  to  render 
them  less  open  in  texture,  and  to  increase  the  per 
cent  of  plant-food  they  contain,  would  become  pro- 
ductive and  very  desirable  lands.  At  present  they 
are  gently  sloping  sandy  plains,  bearing  a  scant  vege- 
tation, but  presenting  ideal  slopes  for  irrigation,  and 
very  many  of  which  are  so  situated  that  water  could 
readily  be  led  upon  them,  both  for  silting  purposes 
and  for  permanent  irrigation,  at  relatively  small  cost. 

Then,  again,  in  the  southern  states,  notably  in  the 
Carolinas  and  Georgia,  there  are  vast  areas  of  sandy 
soil  which  stand  greatly  in  need  of  such  improvement 
as  flooding  with  silt -laden  waters  could  bring  about. 
These  lands  possess  surface  features  and  slopes  which 
readily  permit  of  this  being  done  ;  and,  what  is  more 
to  the  point,  the  streams  are  abundant  and  heavily 


Improvement   of  Land   by    Silting  265 

laden  with  silt  which  they  are  carrying  out  to  sea  in 
great  volumes,  thus  robbing  the  Piedmont  country  at 
a  fearful  rate,  through  lack  of  sufficient  care,  of  its 
most  fertile  soil,  and  transporting  it  directly  through 
the  fields  to  which  it  should  be  applied  and  upon 
which  it  could  readily  be  led  to  great  advantage. 

On  the  sea  coasts  of  these  three  states,  and  par- 
ticularly in  South  Carolina,  there  lie  those  extensive 
and  once  wonderfully  productive  rice  fields  upon  which 
so  much  labor  and  capital  have  been  spent,  but  which 
are  now  largely  abandoned,  since  the  war  of  the  re- 
bellion, for  the  lack  of  sufficient  energy  to  bring  the 
needed  capital  to  the  region. 

Here  are  opportunities  for  capital  to  find  splendid 
permanent  investment  at  good  rates  of  interest,  to 
reclaim  the  vast  rice  fields  now  fast  falling  into  ruin, 
and  to  apply  the  methods  of  warping  to  these  and 
other  lands  until  they  become  what  they  may  certainly 
readily  be  made,  both  thoroughly  healthful  and  the 
richest  of  fields,  adapted  to  a  wide  diversity  of  pro- 
ductions. The  opportunities  for  warping  are  better 
nowhere  in  the  world,  and  there  must  certainly  be  a 
great  future  awaiting  intelligence,  energy  and  capital 
here  to  work  out  the  needed  improvements. 

ALKALI    WATERS    NOT    SUITABLE    FOR    IRRIGATION 

In  many  portions  of  the  world,  and  oftenest  in 
arid  and  semi -arid  regions,  the  waters  of  some 
streams  and  wells,  and  particularly  those  of  lakes, 
are  too  heavily  charged  with  the  salts  of  sodium — 


266  Irrigation  and   Drainage 

common  salt,  sal  soda  and  Glauber's  salt  or  sodium 
chloride,  carbonate  and  sulphate  respectively  —  to 
make  it  advisable  to  use  them  for  the  purposes  of 
irrigation. 

These  salts  are  a  part  of  the  waste  products  of 
soil  production  which  ordinary  vegetation  is  unable  to 
use  with  profit,  and  which  in  countries  of  heavy  rain- 
fall are  washed  out  of  the  soil  nearly  as  rapidly  as 
formed.  Where  these  salts,  however,  do  accumulate 
to  any  notable  extent,  it  is  designated  an  alkali  soil, 
and  will  not  produce  normal  crops  of  many  of  the 
forms  grown  in  plant  husbandry.  The  general  sub- 
ject of  alkalies  and  their  treatment  is  discussed  in 
the  next  chapter,  but  we  cite  below  the  composition 
of  waters  which  have  been  regarded  as  safe  and  as 
unsafe,  without  treatment,  for  purposes  of  irrigation: 

Table  of  safe  and  unsafe  alkali  waters*  in  parts  per  1,000 

Safe  water .  . — Unsafe  water — - 


No.  of 
sample 

Black 
alkali 

White 
alkali 

No.  of 
sample 

Black 
alkali 

White 
alkali 

740 

.022 

.067 

739 

.141 

.135 

742 

.005 

.306 

741 

.009 

8.756 

743 

.007 

.155 

753 

.026 

.818 

744 

.022 

.399 

751 

.011 

7.374 

755 

.009 

.334 

746 

.101 

1.063 

749 

.026 

.306 

747 

.115 

1.082 

750 

.014 

.111 

757 

.036 

1.577 

754 

.026 

.033 

760 

.132 

.084 

It  is  very  unfortunate  that  after  an  analysis  of  a 
sample  of  water  has  shown  accurately  the  amounts  of 
various  elements  it  may  contain,  it  has  not  been  pos- 

"Computed  from  Bull.  29,  p.  4,  Oklahoma  Exp.  Sta. 


Alkali   Water   not   Suitable  for   Irrigation      267 

sible  to  state  with  certainty  precisely  how  these  ele- 
ments were  combined  in  the  sample.  It  is  more 
unfortunate  that  chemists  are  not  agreed  as  to  how 
results  should  be  interpreted,  and  that  different  sys- 
tems are  followed  by  different  analysts.  But  what  is 
most  unfortunate  of  all,  is  that  many  chemists  have 
published  their  computed  results,  as  though  there 
were  but  one  interpretation  of  them,  and  have  not 
given  the  data  upon  which  their  computations  were 
based.  Hence,  we  have  found  it  impossible  to  arrive 
at  what  may  be  regarded  as  the  safe  amount  of 
black  or  white  alkali  an  irrigation  water  may  contain. 
The  table  given  above  represents  the  opinion  of  two 
chemists  as  shaped  by  their  system  of  computing  the 
amounts  of  the  alkalies  in  the  samples  analyzed,  but 
it  must  be  understood  that  another  chemist  using  the 
same  data,  with  a  different  system  of  apportionment, 
would  compute  either  less  or  more  black  alkali  and 
more  or  less  white  alkali  than  the  authors  have 
credited  the  samples  with  as  given  in  the  table  above. 

We  make  this  explanation,  that  the  irrigator  may 
understand  that  when  the  water  from  a  given  source 
is  said  to  contain  .022  parts  in  1,000  of  black  alkali, 
more  allowance  must  be  made  in  regard  to  accuracy 
than  is  required  for  the  statement  that  the  water  car- 
ries in  solution  11.234  grains  of  solids  per  gallon. 

It  should  be  understood  further,  as  will  be  shown 
in  the  next  chapter,  that  a  given  quantity  of  black 
alkali  may  prohibit  the  use  of  the  water  for  irrigation 
purposes  on  one  soil,  when  upon  another  it  may  be 
used  with  perfect  safety. 


268  Irrigation  and  Drainage 

It  sometimes  happens  that  waters  draining  from 
swamp  lands  where  there  has  been  considerable  stag- 
nation, or  where  there  are  too  strong  solutions  of 
humic  acids  or  salts  of  iron,  are  not  suitable  for  irri- 
gation purposes,  and  must  be  avoided.  In  portions 
of  Europe,  too,  there  are  streams  used  for  irrigation 
which  are  known  as  "good"  streams  and  "bad'; 
streams.  Crops  irrigated  from  one  produce  heavier 
yields  than  when  irrigated  from  the  other,  and  cases 
are  cited  where  the  differences  in  yield  are  so  large 
that  they  can  hardly  be  assigned  entirely  to  difference 
in  the  amount  of  plant -food  carried  by  the  two. 


CHAPTER   VIII 

ALKALI  LANDS 
CHARACTERISTICS     OF     ALKALI    LANDS 

THE  use  of  the  term  "alkali  lands,"  as  commonly 
employed,  has  quite  a  loose  or  wide  application.  Hil- 
gard  states  that  in  California  the  term  is  applied 
almost  indiscriminately  to  all  lands  whose  soils  con- 
tain unusual  amounts  of  soluble  salts,  so  that  during 
the  dry  season  or  after  irrigation  the  surface  becomes 
more  or  less  white  with  the  deposits  left  by  the  evapo- 
ration of  the  capillary  waters.  Throughout  much  of 
Minnesota,  Wisconsin,  Michigan,  and  other  states  lying 
within  the  glaciated  areas  of  this  country,  there  are 
black  marsh  soils  which,  after  being  drained  and 
tilled,  come  to  acquire  in  spots  a  deposit  of  white 
salts  at  the  surface  whenever  there  is  much  evapo- 
ration from  the  soil,  and  these  are  frequently  spoken 
of  as  "alkali  spots."  Where  these  salts  are  well 
marked  in  character,  crops  are  killed  out  entirely,  or 
the  growth  is  stunted  much  as  is  true  of  the  black 
alkali  spots  of  arid  regions.  On  the  rice  fields  of 
South  Carolina,  there  appear  during  the  dry  stage 
of  growth  of  the  crop  "alum  spots,"  as  they  are  there 
called,  upon  which  the  rice  may  die  out  or  be  of 
inferior  quality.  Then,  too,  on  the  margins  of  the 


270  Irrigation  and   Drainage 

sea,  where  there  are  low -lying  lands  periodically  in- 
undated by  high  tides,  white  deposits  are  again  left 
when  the  surface  becomes  dry,  and  are  injurious  to 
cultivated  crops  when-  they  have  accumulated  to  suf- 
ficient strength,  and  these  are  sometimes  spoken  of 
as  "alkali  lands." 

In  the  wide  application  of  the  term,  then,  "alkali 
lands"  are  those  upon  which  soluble  salts  have  ac- 
cumulated in  sufficient  quantity,  through  evaporation 
and  capillarity,  to  attract  attention  by  their  usually 
white  appearance  and  their  injurious  effects  upon 
vegetation . 

Hilgard  states  that  "alkali  lands  must  be  pointedly 
distinguished  from  the  salt  lands  of  the  sea  margins 
or  marshes,  from  which  they  differ  both  in  their 
origin  and  essential  nature ; "  and,  in  the  sense  he 
wishes  to  be  understood,  the  distinction  should  be 
made ;  but  there  are  important  advantages,  as  will 
appear,  in  treating  them  all  under  one  head. 

CAUSE    OP    INJURIES     BY    ALKALIES 

When  the  soil  water  about  the  roots  of  plants  or 
germinating  seeds  becomes  sufficiently  strong  with 
salts  in  solution,  the  osmotic  pressure  is  so  modified 
that  a  discharge  of  the  cell  contents  into  the  soil  takes 
place  to  such  an  extent  as  to  produce  what  is  equiva- 
lent to  wilting.  The  cells  are  not  maintained  suffi- 
ciently turgid  to  permit  normal  growth,  or  they  may 
have  the  pressure  so  much  lowered  as  to  cause  death. 
The  case  is  Mke  placing  the  plump  strawberry  or 


Cause   of  Injuries   by   Alkalies    .  271 

currant  in  a  strong  solution  of  sugar,  where  it  is  ob- 
served to  greatly  shrink  in  volume.  So,  too,  it  is 
like  placing  meat  under  strong  brine,  and  the  use  of 
sugar  in  preserves,  where  there  is  so  strong  a  solution 
about  the  products  preserved  that  the  germs  of  decay 
cannot  thrive  in  them. 

This,  then,  is  one  of  the  modes  by  which  the  in- 
jurious effects  of  alkalies  are  produced,  and  it  should 
be  understood  that  it  matters  very  little  what  sub- 
stance may  be  in  solution  in  the  soil  water,  so  long 
as  it  is  there  in  sufficient  quantity  to  produce  the 
osmotic  shrinkage  referred  to. 

Every  one  is  familiar  with  the  fact  that  too  con- 
centrated fertilizers  may  produce  death  to  the  plant, 
and  it  may  be  by  this  action.  Applying  the  principle 
to  the  alkalies  in  the  soil,  it  must  be  recalled  that 
these  compounds  are  all  relatively  very  soluble  in 
water,  so  that  if  only  large  quantities  of  water  con- 
taining even  small  amounts  of  the  salts  are  evaporated 
in  contact  with  the  roots  of  growing  crops,  the  so- 
lution surrounding  the  soil  grains  may  become  too 
strong  for  good  plant  feeding,  and  even  death  may 
result. 

On  this  fundamental  principle  of  action,  it  is  plain 
that  the  black  as  well  as  the  white  alkalies  fall  into 
the  same  category,  and  this,  too,  no  matter  what  may 
be  their  composition,  origin  or  geographic  range. 

It  is  more  than  probable,  if  not  even  certain, 
that  the  action  of  some  of  these  salts  may  be  that  of 
true  poison;  but  the  real  nature  of  toxic  effects  is  not 
as  yet  understood  in  any  full  sense. 


272  Irrigation  and  Drainage 

HOW    ALKALIES    ACCUMULATE    IN    THE    SOIL 

Everywhere  in  the  soil  where  there  are  sufficient 
changes  in  the  air  and  the  moisture,  the  soil  grains 
are  being  broken  down  and  dissolved  by  both  physical 
and  chemical  means,  and  unless  the  rains  are  suffi- 
ciently heavy  to  carry  the  ever -forming  dissolved 
salts  away  in  the  country  drainage,  they  will  be 
brought  to  the  surface  by  capillarity  and  there  con- 
centrated until  precipitated.  The  more  insoluble  of 
the  plant -foods,  and  other  salts  which  are  not  such, 
cannot  charge  the  water  sufficiently  high  to  do  serious 
harm,  hence  in  common  language  and  in  the  sense 
the  term  is  here  used,  they  do  not  become  "alkalies." 

But  with  the  other  salts  the  case  is  different. 
They  are  precipitated  when  the  solution  becomes 
strong  enough,  and  form  deposits  on  the  surface  or 
about  the  roots  in  the  soil  where  water  is  being  re- 
moved, but  before  this  actually  occurs  one  or  both  of 
the  actions  referred  to  above  begins  to  take  place. 

In  arid  regions,  where  the  alkalies  proper  are  most 
abundant,  rains  enough  may  fall  to  slowly  carry  for- 
ward their  formation,  but  not  enough  to  carry  them 
out  of  the  land.  From  the  higher  levels  and  steeper 
slopes  they  are  readily  moved  by  surface  drainage  and 
wind  action  to  the  lower  lands,  where  the  amount 
may  become  so  large  as  to  form  thick  beds.  During 
the  wet  season  of  such  countries,  these  salts  may  sink 
into  the  soil,  but  to  rise  again  when  dry  weather 
restores  the  action  of  capillarity. 

In  the   humid   regions,  there  is  necessarily  an  even 


How   Alkalies   Accumulate   in   Soil  273 

more  rapid  formation  of  all  the  true  alkalies  of  arid 
elimates;  for  fundamentally  similar  rock  ingredients 
are  subjected  to  identical  weathering  processes,  but  of 
a  more  intense  nature,  because  the  rainfall  is  greater. 
If,  therefore,  there  occur  conditions  favorable  to  the 
accumulation  of  the  soluble  salts  formed  at  and  near 
the  surface  of  the  soil,  these  should  be  expected  to 
show  as  alkalies. 

Most  of  the  marsh  lands  of  the  world,  excepting 
those  under  the  influence  of  tide  waters,  owe  their 
wet  character  to  the  underflow  of  ground-water  which 
has  percolated  into  the  adjacent  higher  lands,  and 
which  rises  to  or  near  the  surface  wherever  this  is 
sufficiently  low  to  permit  of  it  doing  so.  When  such 
lands  are  drained,  the  rate  of  surface  evaporation  and 
the  rise  of  capillary  water  from  below  may  exceed 
the  annual  rainfall,  and  thus  lead  to  an  accumulation 
at  the  surface  of  salts  of  .'such  intensity  and  character 
as  to  interfere  with  the  normal  growth  of  plants. 

It  must  be  kept  in  mind  that  where  the  ground -water 
level  is  near  the  surface,  the  rate  of  capillary  rise  may 
many  times  exceed  what  it  could  be  under  other  con- 
ditions, and  since  the  rate  of  evaporation  is  most 
rapid  where  the  surface  soil  is  wettest,  the  conditions 
are  extremely  favorable  for  the  accumulation  of  solu- 
ble salts  at  the  surface  of  marsh  lands  in  humid 
climates  after  they  have  been  di-iined.  The  waters 
leaching  through  the  more  open,  higher  lands  become 
charged  with  salts,  and  as  these  waters  come  again 
near  the  surface  under  the  low  areas  they  are  raised 
by  capillarity  and  evaporated,  leaving  the  salts  which 


274  Irrigation  and   Drainage 

had  been  taken  up  along  the  underground  path 
to  accumulate  over  the  low -lying  lands,  and  since 
the  evaporation  of  12  inches  of  salt -laden  water  may 
produce  more  deposits  than  the  same  depth  of  rain 
would  be  sure  to  remove  in  leaching  downward,  the 
chances  are  favorable  to  accumulation. 

INTENSIVE    FARMING    MAY    TEND    TO     THE    ACCUMU- 
LATION   OF    ALKALIES 

It  has  already  been  pointed  out  that  during  the 
growing  season,  after  vegetation  has  come  into  full 
action,  nearly  all  of  the  rains  which  fall  in  humid 
climates  are  retained  near  the  surface  until  they  are 
evaporated,  either  through  the  growing  crop  or  from 
the  soil,  and  since  these  waters  tend  to  form  salts 
when  they  are  in  contact  with  the  soil  grainfe,  they 
must  tend  to  increase  the  salt  content  near  the  surface. 
It  is  plain,  too,  that  the  heavier  the  crops  produced 
and  the  greater  the  number  of  them  in  the  season,  the 
less  is  likely  to  be  the  loss  of  any  water  from  the  field 
by  under -drainage  ;  hence  the  greater  the  tendency 
for  soluble  salts  to  accumulate.  Then,  if  during  the 
winter  season  of  a  country  the  rainfall  is  deficient,  so 
that  little  leaching  can  take  place,  conditions  become 
still  more  favorable  for  the  accumulation  of  alkalies. 

Further  than  this,  if  irrigation  is  practiced  during 
the  growing  season  only,  and  this  water  also  is 
evaporated  from  the  soil  in  addition  to  the  natural 
rainfall,  it  is  plain  that  the  amount  of  soluble  salts 
in  the  soil  must  increase,  both  on  account  of  that 
which  may  have  been  in  the  water  applied,  and  that 


Amount   oj  Alkali   Injurious  275 

\vhich  this  additional  water  may  have  been  instrumental 
in  producing  from  the  soil  on  the  spot  through  the 
processes  of  weathering. 

Indeed,  the  more  we  study  and  reflect  upon  this 
problem,  the  more  we  are  led  to  fear  that  in  all  arid 
climates,  where  irrigation  is  practiced,  it  will  not  be 
found  sufficient  to  apply  simply  enough  water  to  the 
soil  to  meet  the  needs  of  the  crop  growing  upon  the 
ground  at  the  time,  but,  on  the  contrary,  there  must 
be  enough  more  water  applied  to  take  up  and  carry 
away  into  drainage  channels  and  out  of  the  country 
to  the  sea  not  only  the  soluble  salts  which  the  irriga- 
tion waters  carry,  but  also  those  which  it  causes  to  be 
produced  from  the  soil  and  subsoil.  In  other  words, 
it  appears  that  an  excess  of  soluble  salts  in  a  thoroughly 
irrigated  field  is  not  only  a  normal  but  an  inevitable 
condition,  unless  sufficient  leaching  takes  place;  and 
if  this  is  true,  the  sparing  use  of  water  can  only 
increase  the  number  of  years  required  to  bring  the 
salts  up  to  the  danger  point  of  concentration. 

AMOUNT     OF     SOLUBLE     SALTS     WHICH    ARE     INJURIOUS 
IN     SOILS 

Storer  states  that  it  is  a  matter  of  record  that  long 
experience  in  the  south  of  France  has  shown  that  any 
soil  which  becomes  visibly  covered  with  a  slight  in- 
crusation  of  salt  in  times  of  drought  is  improper  for 
cultivation,  unless  special  pains  are  taken  to  prevent 
the  surface  from  becoming  dry. 

Plagniol  insisted,  in  his  time,  that  soils  containing 
more  than  2  per  cent  of  salt  are  unfit  for  the  growth 


276  Irrigation  and   Drainage 

of  any  other  than  samphire,  saltwort,  and  the  like, 
and  that  even  these  cannot  thrive  when  the  salt 
becomes  as  high  as  5  per  cent. 

Deherain  concludes,  from  his  studies  in  France, 
that  while  soils  kept  very  moist  may  produce  crops 
even  when  2  per  cent  of  salt  is  present,  yet  if  the 
soils  dry  out  badly  they  become  sterile  with  no  more 
than  1  per  cent  present.  Gasparin  has  maintained, 
however,  that  while  soils  containing  .02  per  cent  of 
salt  may  produce  good  crops  of  wheat,  .2  per  cent 
is  more  than  this  crop  can  bear. 

Speaking,  next,  of  the  alkali  salts  of  arid  climates, 
we  may  cite  some  of  the  data  procured  by  Hilgard  in 
his  extended  and  careful  studies  of  the  alkali  problems 
of  California.  At  their  Tulare  Experiment  Station, 
he  gives  both  the  amount  and  the  distribution  of 
soluble  salts  in  the  surface  18  inches  of  soil  where, 
in  one  case,  barley  grew  to  a  height  of  4  feet,  and  in 
another  the  amounts  of  the  salt  were  so  great  that 
this  crop  would  not  thrive.  The  data  which  we  give 
in  tabular  form  have  been  read  from  his  plotted  curves, 
hence  the  values  must  be  regarded  as  not  quite  exact. 

Table  showing  amount  and  composition  of  alkali  salts  in  parts  per  100 
Taken  September,  1894,  Tulare  Experiment  Station,  California 

Ground  upon  which  barley  Ground  upon  which  barley 

grew  4  feet  high  did  not  grow 

Depth  in     Sodium    Sodium    Com'n    Total  Sodium    Sodium    Com'n    Total 

3-in        carb'ate  sulphate      salt     soluble  carb'ate   sulphate     salt       soluble 

tions  NaaCOs,  Na2SO4  NaCl     salts     Na2CO3  Na*SO4  NaCl     salts 


Oto    Sin...     .008  .68  .36         1.2  .07  1.22  .68          2.44 


3  to   6  in... 

.009 

.26 

.07 

.34 

.1 

.16 

.1 

.38 

6  to   9  in... 

.013 

.1 

.03 

.168 

.099 

.11 

.05 

.28 

9  to  12  in... 

.024 

.057 

.02 

.143 

.099 

.148 

.06 

.334 

12  to  15  in... 

.038 

.037 

.02 

.119 

.14 

.1 

.04 

.29 

15  to  18  in.  .  . 

.04 

.02 

.02 

.09 

.18 

.06 

.02 

.263 

Amount   of  Alkali   Injurious 


277 


Sodium  nitrate  is  also  given  in  these  cases  as  a 
constituent,  but  as  this  may  be  regarded  as  a  plant- 
food,  we  have  omitted  it  from  the  table.  It  will  be 
observed  that  the  total  soluble  salts  in  the  surface  3 
inches  where  the  barley  grew  well  was  about  half  that 
found  in  the  case  where  it  won  Id  not  grow,  the  amounts 
in  the  two  cases  being  1.2  and  2.44  per  cent  of  the  soil. 
The  difference  between  the  amounts  of  the  black  alkali 
in  the  two  cases  stands  as  8  to  70,  or  much  more. 

Referring  to  the  possibility  of  these  salts  interfering 
with  plant  life  simply  on  account  of  their  plasmolitic 
action,  it  may  be  said  that  DeVries  found,  as  repre- 
sented in  Fig.  49,  that  when  the  living  cells  of  a  plant 
were  immersed  in  a  4  per  cent  solution  of  potassium 


1234 

Pig.  49.     Effect  of  too  strong  solution  of  potassium  nitrate  on  the 
protoplasm  of  plant  cells.     (After  DeVries.) 

nitrate,  there  was  first  a  shrinkage  in  volume  through 
a  loss  of  water,  as  shown  between  1  and  2.  When 
the  solution  was  given  a  strength  of  6  per  cent,  then, 
in  addition  to  the  change  in  volume,  the  protoplasmic 
lining  P  began  to  shrink  away  from  the  cell  wall  h, 
as  shown  at  3,  and  when  the  strength  of  the  solution 
was  made  10  per  cent,  the  conditions  shown  in  4  were 


278  Irrigation  and    Drainage 

produced.  When  such  conditions  as  those  represented 
in  3  and  4  are  set  up,  marked  wilting  must  result  and 
growth  be  brought  nearly  or  quite  to  a  standstill. 

It  is  not  possible  to  state  with  certainty  what 
strength  of  salt  solution  existed  in  the  soil  moisture  in 
the  cases  cited  above,  but  an  approximate  estimate 
may  be  made.  Hilgard's  analyses  show,  in  the  case 
of  the  sample  from  where  barley  would  not  grow, 
that  the  soluble  alkalies  amounted  to  2.44  pounds  per 
100  pounds  of  soil.  If  these  salts  were  all  in  solution 
in  the  soil -water,  and  if  the  soil -water  amounted  to 
30  per  cent  of  the  dry  weight  of  the  soil,  then  the 
salts  in  solution  would  have  a  strength  of  8.13  per 
cent.  But  if  only  15  per  cent  of  moisture  existed  in 
the  soil,  as  might  easily  have  been  the  case,  and  all 
the  salts  were  in  solution,  then  its  strength  would 
have  been  double  that  above,  and  much  stronger  than 
DeVries7  most  severe  trial.  It  does  not  appear  im- 
probable, therefore,  that  even  were  there  no  poisonous 
effect  exerted  upon  the  barley  by  the  salts  in  the  soil, 
the  plants  could  not  have  grown,  on  account  of  the  wilt- 
ing which  would  have  resulted  from  the  presence  of 
too  strong  a  salt  solution  outside  the  cell  walls  of  the 
root -hairs  in  the  soil. 

COMPOSITION  f  OF     ALKALI     SALTS 

To  show  the  character  of  the  salts  which  accumu- 
late in  the  manner  under  consideration,  we  have 
computed  the  mean  composition  from  a  number  of 
analyses  as  given  by  Hilgard,  and  the  results  are 
stated  in  the  table  which  follows  ; 


Composition   of  Alkali   Salts  •    279 

Table  showing  composition  of  alkali  salts 

Acids  and  bases                                                California  Washington  Montana 

Silica  (Si02)   1.663  1.552  .42 

Potash  (K2O) 3.602  9.588  1.774 

Soda(Na2O) ..     40.058  45.387  30.442 

Lime  (CaO) 519  .048  1.4b4 

Magnesia  (MgO) 258  .115  5.956 

Peroxide   of    iron  (Fe2O3)  and  alu- 
mina (A1203) 079  .028  .04 

Phosphoric  acid  (P2O5) 1.457  .81  .012 

Sulphuric  acid  ( SO3 ) 1 8. 946  2.12  44.482 

Nitric  acid  (N205) 1.923  .000  1.074 

Carbonic  acid  (CO2) 13.982  34.058  2.208 

Chlorine  (Cl) 7.46  1.077  5.148 

Ammonia  (NH3) 047  .000  .000 

Organic  matter  and  water  of  crystalli- 
zation. .                              11.282  5.073  8.136 


101.276         99.856      101.156 
Less  excess  of  oxygen  corresponding 

to  Cl 1.623  .238          1.166 


Totals 99.653         99.618  99.990 

When    these    results    are    computed    as    salts    they 
stand,  according  to   Hilgard,  as  expressed  below: 

Table  showing  composition  of  soluble  portions  of  alkali  salts 

California    Washington  Montana 

Potassium  Sulphate  (K2SO4) 6.796           3.715  3.774 

carbonate  (K2CO3) 732          12.378  .000 

Sodium  sulphate  (Na2SO4) 31.956             .000  61.432 

"        nitrate  (NaNO3) 3.64               .000  1.878 

carbonate  (Na2C03) 39.413         80.053  2.94 

"        chloride  (NaCl) 14.703           1.913  9.864 

phosphate  (HNa2PO4) 2.273           1.943  .000 

Magnesium  sulphate  (MgSO4 ) 307             .000  21 .12 

Ammonium  carbonate  (NH42CO3)...         .157             .000  .000 


280  Irrigation  and   Drainage 

It  will  be  seen  from  these  two  tables  that  there 
may  be  associated  with  the  undesirable  salts  quite 
notable  quantities  of  others  which  are  valuable  plant- 
foods.  This  is  as  should  be  expected,  for  the  more 
soluble  plant -foods,  as  well  as  the  salts  not  suitable 
for  plant  life,  must  be  moved  by  the  same  waters, 
and  tend  to  collect  with  them. 

Hilgard  points  out  that  where  the  soluble  phos- 
phates and .  considerable  quantities  of  humus  are  asso- 
ciated with  the  sodium  carbonate  or  black  alkali,  it  is 
often  desirable  to  first  transform  the  sodium  carbo- 
nate into  sodium  sulphate  through  an  application  of 
land  plaster.  By  so  doing  both  the  humus  and 
phosphates  are  rendered  insoluble,  but  not  unavaila- 
ble for  plant -food,  hence  may  be  retained  in  the  soil 
for  future  use  after  the  alkalies,  which  are  harmful, 
have  been  washed  out  or  otherwise  disposed  of.  This 
is  an  important  suggestion  to  keep  in  mind. 

THE  APPEARANCE  OF  VEGETATION  ON 
ALKALI  LANDS 

When  cultivated  crops  are  grown  upon  alkali  lands, 
characteristic  effects  are  produced  which  serve  to  point 
out  the  difficulty  with  the  soil  and  the  remedy  which 
should  be  applied.  If  the  salts  in  the  soil  are  not  too 
concentrated,  the  crop  may  germinate  in  a  perfectly 
normal  manner,  but  after  a  time  begin  to  languish  in 
spots,  and  remain  dwarfed  in  stature  or  entirely  die 
out.  It  is  very  common  to  see  a  field  upon  which  the 
crops  present  an  extremely  uneven  stand,  some  areas 


Appearance   of   Vegetation   on   Alkali   Lands     281 

being  entirely  destitute  of  plants,  or  bearing  only  those 
which  are  small,  while  closely  adjacent  spots  may  be 
covered  with  large,  vigorous,  and  perfectly  normal 
growths.  Fig.  50  illustrates  this  feature,  as  it  is  ex- 
hibited in  the  San  Joaquiii  valley  of  California,  and 
Fig.  51  shows  essentially  similar  features  as  they  de- 
velop on  black  marsh  soils  in  Wisconsin  after  they  have 
been  tile -drained.  In  this  latter  case,  the  crop  on  the 
afflicted  areas  comes  to  an  early  standstill,  or  a  plant 


Fig.  50.    Vegetation  on  alkali  lands  in  California.     (Hilgard.) 

may  go  through  all  the  phases  of  growth,  reaching 
maturity,  but  with  a  very  dwarf  habit,  so  that  maize 
in  tassel  and  ear  may  not  stand  higher  than  6  to  10 
inches,  while  close  by  may  stand  another  hill  or  group 
of  them  where  the  growth  has  been  unusually  rank 
and  luxuriant.  On  these  soils  the  afflicted  plants  pos- 
sess a  very  imperfect  root  system,  the  older  roots 
turning1  brown,  soft,  and  apparently  decaying,  while 
new  ones  form  above. 


282  Irrigation  and   Drainage 

DISTRIBUTION    OF    ALKALIES    IN    THE    SOIL 

The  position  in  the  soil  where  the  alkalies  may  be 
found  in  greatest  abundance  varies  under  different  con- 


Fig.  51.    Growth  of  maize  on  black  marsh  soil  in  Wisconsin. 

ditions.  Where  there  is  a  large  and  prolonged  evapo- 
ration at  the  surface,  the  alkalies  may  be  nearly  all 
collected  within  the  surface  3  or  4  inches,  and  hence  be- 
come so  strong  as  to  do  serious  injury,  when  if  this 


Distribution   of  Alkali   in    Soil  283 

concentration  had  been  prevented  no  serious  harm 
could  have  resulted.  So,  too,  if  the  salts  have  been 
gathered  into  a  thin  layer  near  the  surface,  heavy 
rains  or  an  application  of  water  by  irrigation  may 
move  them  at  once  bodily  and  nearly  completely  to  a 
depth  of  1,  2  or  3  feet,  varying  with  the  amount  of 
water  applied,  the  capacity  of  the  soil  to  store  water, 
and  the  amount  of  water  it  contained  previous  to  the 
application.  Under  these  circumstances,  it  is  plain 
that  fields  afflicted  with  alkalies  may  exhibit  at  one 
time  the  most  intense  symptoms  of  poisoning  and  at 
another  be  entirely  free  from  them,  so  far  as  revealed 
by  a  crop  upon  the  ground. 

In  examining  soils  for  alkalies,  it  is  a  matter  of 
the  utmost  importance  to  recognize  that  the  distribu- 
tion of  them  is  extremely  liable  to  be  capricious,  and 
that  it  is  easy  to  overlook  their  presence  by  stopping 
the  sampling  of  the  soil  just  short  .  of  the  level  at 
which  all  of  the  alkalies  had  chanced  to  be  concen- 
trated ;  or,  again,  by  taking  a  sample  of  the  1st,  2d 
and  4th  feet,  or  of  the  1st,  3d  and  4th  feet  when,  ow- 
ing to  the  capricious  distribution,  all  of  the  salts  had 
been  collected  in  the  2d  or  3d  foot,  and  thus  were 
overlooked  because  it  may  have  been  thought  not 
worth  while  to  make  a  complete  section  of  the  soil 
in  question. 

CONDITIONS     WHICH     MODIFY    THE     DISTRIBUTION 
OF    ALKALIES     IN     SOIL 

If  the  surface  of  the  ground  is  kept  naked  and 
compact,  so  that  the  rate  of  evaporation  may  be 


284  Irrigation  and   Drainage 

strong,  the  alkalies  will  necessarily  be  brought  to  the 
surface  and  become  concentrated  there,  hence  in  posi- 
tion to  do  the  greatest  harm  to  growing  crops. 

If  thorough  tillage  is  practiced  early,  so  that  but 
little  water  is  evaporated  except  that  which  passes 
through  the  roots  of  the  crop,  then  the  salts  cannot 
become  concentrated  in  a  narrow  zone,  but,  on  the 
contrary,  will  be  left  all  through  the  soil  where  the 
roots  which  are  taking  water  are  distributed.  In  those 
cases,  therefore,  where  the  general  soil  water  is  not 
too  highly  concentrated  to  permit?  normal  growth, 
crops  may  prosper  so  long  as  the  surface  is  kept 
shaded  and  thoroughly  tilled. 

It  must  be  observed,  however,  and  kept  in  mind, 
that  the  roots  of  plants  cannot  withdraw  moisture  from 
a  soil  without  at  the  same  time  tending  to  concentrate 
the  salts  in  solution  in  the  zone  where  the  roots  do 
their  feeding ;  hence,  that  if  alkali  waters  are  being 
used  for  irrigation,  and  in  the  long  run  if  the  purest 
waters  are  being  used  under  conditions  of  no  drainage, 
sooner  or  later  the  soil  of  the  root  zone  must  become 
so  highly  charged  with  the  alkali  salts  that  reduced 
yields  are  inevitable. 

USE  OF  LAND  PLASTER  TO  DESTROY  BLACK  ALKALI 

Hilgard  long  since  pointed  out  that  in  regions 
where  the  water  contained  sulphate  of  lime  in  solu- 
tion, there  sodium  carbonate  was  absent,  or  existed  in 
auch  small  quantities  as  not  to  be  harmful  to  crops,  and 
he  early  saw  and  recommended,  that  where  fields  were 


Land    Plaster  for   Black   Alkali  285 

troubled  with  black  alkali  in  not  too  large  quantities, 
land  plaster  could  be  used  as  a  fertilizer,  which  would 
have  the  effect  of  changing  the  sodium  carbonate  into 
the  less  harmful  sodium  sulphate,  and  in  this  way 
transform  sterile  lands  into  those  which  are  capable 
of  being  worked  at  a  profit.  He  clearly  saw,  however, 
that  such  a  remedy  was  not  an  absolute  corrective, 
but  rather  of  the  nature  of  a  substitution  of  a  lesser 
for  a  greater  evil,  as,  sooner  or  later,  the  sodium  sul- 
phate comes  to  be  too  strong  to  be  endured. 

Hilgard  has  further  pointed  out  that  the  application 
of  land  plaster  to  a  soil  rich  in  sodium  carbonate  very 
greatly  improves  the  texture  or  mechanical  condition 
of  such  a  soil,  because  black  alkali  tends  to  break 
down  the  granular  structure  of  clay  soils,  and  thus 
puddles  them  and  renders  them  nearly  uninhabitable 
by  most  plants,  largely  on  account  of  their  bad 
mechanical  condition. 

Still  further  has  Hilgard  pointed  out  that  the  pres- 
ence of  black  alkali  in  a  soil -water  tends  to  dissolve 
the  humic  nitrogen  and  the  comparatively  insoluble 
phosphates  of  the  soil,  so  that  if  leaching  is  taking 
place  under  the  influence  of  a  water  containing  much 
sodium  carbonate,  great  harm  is  being  done  by  depriv- 
ing the  soil  of  two  of  its  most  important  ingredients 
of  plant -food.  Hence  if  alkali  lands  are  to  be  im- 
proved by  drainage,  this  should  not  be  done  until 
steps  have  been  taken  to  first  transform  the  sodium 
carbonate  to  the  sulphate,  and  thus  precipitate  the 
humic  nitrogen  and  the  phosphate  so  that  these  may 
be  retained. 


286  Irrigation  and   Drainage 

KINDS     OF    SOIL    WHICH    SOONEST    DEVELOP    ALKALI 

Where  alkali  waters  are  used  for  purposes  of  irri- 
gation, and  where  sweet  waters  are  being  used  under 
conditions  of  little  or  no  drainage,  the  clayey  soils 
are  the  ones  which  soonest  begin  to  show  the  bad 
effects  of  concentrated  salts.  This  is  so  for  many 
reasons. 

In  the  first  place,  the  soils  of  clayey  texture,  as  has 
been  established  by  experiments  recorded  on  page  201, 
are  not  as  effective  mulches  as  the  sandy  soils,  hence, 
even  where  thorough  tillage  and  shade  are  resorted 
to,  there  must  necessarily  be  a  larger  rise  of  salt- 
bearing  water  to  the  surface  to  produce  accumulation 
than  is  the  case  with  the  coarse,  sandy  soils. 

Iii  the  second  place,  when  water  is  applied  to  a 
sandy  soil,  not  nearly  as  much  remains  adhering  to 
the  surface  of  the  soil  grains  and  entangled  between 
them,  so  that  it  quickly  spreads  downward  farther 
below  the  surface  than  is  the  case  with  the  clay.  This 
being  true,  it  takes  less  water  to  produce  effective 
drainage,  and  the  roots  of  the  crop  spreading  farther 
in  the  sands,  the  salts  cannot  become  concentrated  as 
they  may  in  the  clays. 

In  the  third  place,  since  more  water  is  held  in 
contact  with  the  soil  grains  of  the  clays,  and  since 
the  total  surface  for  chemical  action  to  take  place  upon 
is  very  much  larger  in  the  clayey  soils  than  in  the 
sands,  it  is  plain  that  soluble  salts,  including  alkalies, 
may  form  more  rapidly  in  one  case  than  in  the  other, 
and  hence,  that  the  open,  sandy  soils  cannot  become 


Correction    of  Alkali    Waters  287 

alkali    lands   except    under   conditions   which   are   ex- 
tremely .favorable  to  their  formation. 

CORRECTION    OP    ALKALI    WATERS    BEFORE    USE    IN 
IRRIGATION 

In  case  an  irrigation  water  is  known  to  contain  an 
injurious  amount  of  black  alkali,  it  is  possible  to  con- 
vert this  into  the  sodium  sulphate  by  the  use  of  land 
plaster  in  the  water  before  applying  it  to  the  field. 

To  do  this  in  the  cases  where  water  is  stored  in 
reservoirs,  it  is  possible  to  arrange  cribs  of  uncrushed 
gypsum  through  which  the  water  flows  in  entering  the 
reservoir,  and  if  this  should  not  be  sufficient  to  effect 
the  whole  change,  other  cribs  could  be  built  at  other 
points  in  the  reservoir  and  at  the  outlet.  So,  too, 
where  the  lateral  is  taken  to  the  field,  it  would  often 
not  be  difficult  to  arrange  so  that  the  water  flowed 
through  a  basin,  wide  ditch  or  reservoir  in  which  hang 
crates  of  gypsum,  over  which  the  water  passes  on  its 
way  to  the  field,  or  the  same  method  may  be  applied 
in  the  larger  canals. 

If  the  fields  upon  which  alkali  waters  must  be  used 
are  heavy  and  especially  likely  to  be  injured  by  the 
puddling  process,  it  would  seem  to  be  much  the  better 
method  to  apply  the  corrective  for  black  alkali  to  the 
water  itself,  rather  than  to  the  field,  after  there  has 
been  opportunity  for  some  damage  to  be  done. 

DRAINAGE  THE  ULTIMATE  REMEDY  FOR  ALKALI  LANDS 

If  it  is  true  that  alkali  salts  are  formed  from  the 
decomposition  of  the  soil  and  subsoil  through  the  ac- 


288  Irrigation  and   Drainage 

tion  of  water  and  air,  it  is  only  too  plain  that  where 
conditions  are  persistently  maintained  which  allow  the 
formation  of  the  salts  without  permitting  them  to  be 
removed  by  any  cause  whatsoever,  there .  must  come  a 
time,  sooner  or  later,  when  the  amounts  produced  and 
accumulated  in  the  soil  shall  reach  the  degree  of  con- 
centration which  is  intolerable  to  cultivated  crops. 
Under  the  natural  conditions  of  rainy  countries,  there 
is  usually  a  sufficient  amount  of  leaching  to  permit 
the  white  and  black  alkalies  to  be  borne  away  in  the 
country  drainage  with  sufficient  completeness  to  pre- 
vent their  effects  attracting  general  attention,  and  if 
the  same  processes  obtained  in  irrigated  countries,  it 
is  plain  that  in  these,  too,  the  difficulties  would  not 
arise.  The  conclusion  is  irresistible,  therefore,  that  some 
method  must  be  devised  by  which,  periodically  at  least, 
sufficient  water  is  applied  to  irrigated  fields  to  pick  up 
and  carry  out  of  the  country  the  soluble  alkali  salts 
which  are  fatal  to  cultivated  crops. 

In  the  old-time  irrigation  of  the  Nile  valley,  the 
greater  part  of  the  land  was  under  basin  irrigation, 
and  thus  thoroughly  washed  during  some  fifty  days 
every  year.  Lands  not  so  treated  were  the  lighter 
sandy  soils  near  the  Nile,  protected  by  only  slight 
banks  from  inundation,  and  these  dykes  usually  gave 
way  as  often  as  every  seven  or  eight  years,  so  that 
they,  too,  were  occasionally  thoroughly  flooded.  Un- 
der this  system  of  washing  and  drainage,  the  fields  of 
the  Nile  were  kept  free  from  alkalies  for  thousands  of 
years.  But  at  the  present  time,  when  what  are  called 
more  rational  methods  are  being  applied,  but  with  no 


Drainage    the    Ultimate   Remedy  for   Alkali     289 

attention  being  paid  to  freeing  the  soil  from  the  ac- 
cumulation of  alkalies,  these  salts  have  been  concen- 
trated to  so  serious  an  extent  that  already  many  acres 
have  been  abandoned. 

The  probabilities  are  that  long,  long  ago  the  same 
more  rational  methods  (!)  now  being  practiced  had 
been  tried  and  found  inadequate  or  inapplicable,  on 
account  of  the  accumulation  of  alkalies  which  they 
permitted,  and  the  old  irrigators  learned  to  be  content 
with  a  system  which,  although  more  wasteful  in  some 
ways,  still  kept  the  dreaded  alkalies  under  control. 

It  is  not  improbable  that  if  the  full  history  of 
many  abandoned  ancient  irrigation  systems  could  be 
known,  it  would  be  found  that,  not  being  able  to 
command  water  sufficient  for  drainage,  or  not  appreci- 
ating its  need,  alkalies  were  allowed  to  accumulate 
until  the  lands  were  no  longer  productive. 

It  is  a  noteworthy  fact  that  the  excessive  develop- 
ment of  alkalies  in  India,  as  well  as  in  Egypt  and 
California,  are  the  results  of  irrigation  practices 
modern  in  their  origin  and  modes,  and  instituted  by 
people  lacking  in  the  traditions  of  the  ancient  irri- 
gators, who  had  worked  these  same  lands  for  thousands 
of  years  before.  The  alkali  lands  of  today,  in  their 
intense  form,  are  of  modern  origin,  due  to  practices 
which  are  evidently  inadmissible,  and  which,  in  .all 
probability,  were  known  to  be  so  by  the  people  whom 
our  modern  civilization  has  supplanted. 

The  subject  of  Drainage  will  be  discussed  in 
Part  II. 


CHAPTER  IX 

SUPPLYING    WATER   FOR  IRRIGATION. 

IT  is  not  the  purpose  in  this  chapter,  nor  has  it 
been  the  purpose  in  this  work,  to  discuss  the  larger 
questions  of  water  supply  for  irrigation.  These  are 
quite  purely  engineering  problems,  involving  a  mass 
of  detail  and  technicality  which  concern  the  agricul- 
turist only  in  the  final  results  which  they  bring  to 
him  ;  hence,  he  is  interested  in  them  only  in  a 
general  way. 

We  shall  aim,  therefore,  in  dealing  with  the  supply 
of  water  to  whole  communities  for  purposes  of  irri- 
gation, to  present  only  a  general  idea  of  the  systems 
which  have  been  evolved  and  adopted  under  the 
varying  conditions  of  different  countries  and  climates, 
reserving  the  main  part  of  the  chapter  for  the  dis- 
cussion in  detail  of  the  cases  where  water  is  supplied 
by  individual  effort  for  individual  use. 

DIVERTING    RIVER    WATERS 

By  far  the  most  general  method  of  supplying  water  for  the 
use  of  large  sections  of  country  is  to  throw  a  dam  across  a  stream, 
and  divert  from  the  channel  a  portion  of  the  river  water, 
leading  it  out  into  the  district  to  be  watered  through  canals 
provided  for  the  purpose. 

(290) 


Diverting    Water  from    Streams 


291 


An  excellent  example  of  such  a  large  scale  system  is  repre- 
sented in  Fig.  52,  which  shows  the  Sirhind  canal,  taken  out  of 
the  Sutlej  river,  in  the  Punjab  of  India,  at  Eupar.  This  canal 
was  designed  to  have  a  carrying  capacity  of  6,000  cubic  feet 
per  second,  and  extends  as  a  single  main  trunk  41  miles,  where 
it  is  bisected.  Three  miles  further  on  the  western  trunk  it  is 
divided  again,  forming  two  canals  of  100  and  125  miles  respec- 
tively, while  the  eastern  main  branch  divides  into  three  of  90,  56 


Fig.  52.     Sirhind  canal  system,  Punjab,  India. 
(Wilson,  U.  S.  Geol.  Stirvey.) 

and  25  miles  respectively.  There  are  in  the  whole  system  41  miles 
of  main  canal,  503  miles  of  main  branches,  and  4,407  miles  of 
main  distributaries,  supplying  800,000  acres  of  irrigable  lands. 

The  annual  rainfall  of  the  region  in  which  this  system  has 
been  developed  varies  from  10  to  35  inches.  The  sytem  is  said 
to  have  cost  $7,831,000,  and  to  have  yielded  in  1899  an  annual 
revenue  of  2%  per  cent  on  the  cost,  although  less  than  half  of 
the  available  land  has  yet  been  brought  to  use  the  water. 

We  have  already  referred  to  the  head   gates  of  one  of  the 


292 


Irrigation  and   Drainage 


canals  of  the  Durance,  and  given  an  engraving  of  it  in  Fig.  48. 
In  further  illustration  of  the  methods  used  in  diverting  by  gravity 
the  water  of  a  stream  for  purposes  of  irrigation,  Fig.  53  shows 
diagram  matically  how  the  Kern  Island  canal,  in  California,  is 
taken  from  the  Kern  river,  together  with  the  position  of  the 
regulator,  and  of  the  waste  gate  by  which  the  unused  water  finds 


Fig.  53.    Head  of  Kern  'island  canal,  California. 
(Grunsky,  U.  S.  Geol.  Survey.) 

its  way  back  into  the  channel.  Figs.  54  and  55  are  bird's-eye 
views  of  the  same  thing,  showing  the  regulator  and  the  waste  gate. 
In  Fig.  56  is  given  a  nearer  view,  looking  across  the  canal  over 
the  waste  gate,  the  regulator  being  at  the  left. 

In  aligning  these  canals,  they  are  led  back  from  the  stream 
as  far  as  the  general  fall  of  the  valley  will  permit,  and  in  taking 
out  the  laterals  and  distributaries,  these  are  carried  to  the  highest 
portions  of  the  fields  to  be  irrigated,  and  at  the  same  time  are 


Diverting    Water  from    Streams 


293 


held  as  far  as  possible  above  the  level  of  the  surface,  in  order 
that  there  shall  be  no  difficulty  in  taking  out  the  water  upon  the 
land  to  which  it  is  to  be  applied. 

If   reference    is    again   made   to    Fig.  52,  it  will   be   easy  to 


Fig.  54.     Bird's-eye  view  of  head  of  Kern  Island  canal,  looking  up  stream. 
(Grunsky,  U.  S.  Geol.  Survey.) 

understand  that  where  such  vast  volumes  of  water  are  taken 
across  a  country  in  open  canals,  carried  as  high  as  possible  and 
even  above  the  surface,  there  must  necessarily  be  an  extensive 
seepage  into  the  subsoil,  which  in  the  course  of  time  must 
tend  to  raise  the  original  ground -water  level  much  nearer  the 


294 


Irrigation  and   Drainage 


surface,  and    tend   to   develop  swamps    in   the    lowest -lying   and 
flattest  sections  of  the  area  traversed. 

It  is  further  clear,  too,  that  under  the  conditions   set  up  by 
such  a  network    of   canals,  there    must   be  a  much  more    rapid 


Fig.  55.    Head  of  Kern  Island  canal,  looking  down  stream. 
(Grunsky,  U.  S.  Geol.  Survey.) 

action  of  water  upon  the  subsoil  to  form  alkalies  ;  and  since, 
with  the  nearer  approach  of  the  ground  water  to  the  surface,  the 
capillary  action  and  evaporation  must  be  much  augmented,  it 
is  plain  that  the  deterioration  of  land  through  the  increase  of 
alkalies  is  the  thing  to  be  feared  rather  than  wondered  at. 


Diverting    Water  from   Streams  295 

In  laying  out  such  a  system  of  irrigation  as  the  one  under 
consideration,  it  thus  becomes  a  matter  of  the  greatest  moment 
that  proper  attention  be  paid  to  drainage,  and  that  ample  pro- 
vision be  made  for  it.  If  this  is  not  done,  a  relatively  few 


Fig.  56.    Waste  gate  and  regulator  at  head  of  Kern  Island  canal,  looking  across 
the  canal.     (Grtmsky,  U.  S.  G-eol.  Survey.) 

years  are  almost  certain  to  convert  a  great  benefit  into  one  of 
the  most  serious  of.  scourges.  Drinking  waters  are  likely  to 
become  polluted,  malarial  fevers  prevalent,  and  the  land  unpro- 
ductive, both  on  account  of  water-logging  and  the  excessive 
accumulation  of  alkalies. 


296  Irrigation   and   Drainage 

The  dangers  in  this  direction  will  be  least  in  countries  where 
the  natural  drainage  facilities  are  best  ;  where  the  streams,  draws 
and  washes  are  sunk  deepest  below  the  surface  of  the  fields; 
and  where  the  subsoil  is  the  most  open,  thus  providing  an  easy 
escape  of  the  seepage  waters  into  the  natural  drainage  channels. 
Under  such  conditions  as  these,  it  would  be  only  the  most  waste- 
ful, extravagant  and  inexcusable  use  of  water,  with  no  attention 
to  proper  methods  of  tillage,  which  could  lead  to  the  evils 
pointed  out. 

But,  on  the  other  hand,  in  countries  where  the  natural 
drainage  lines  are  shallow  and  few,  and  where  the  soil  and 
subsoil  are  close,  it  will  require  the  greatest  vigilance  and  the 
rarest  skill  and  judgment  to  avert  the  evils  of  swamping,  the 
development  of  a  malarial  atmosphere,  and  the  formation  of 
alkalies.  If,  in  addition  to  the  conditions  last  pointed  out,  the 
irrigation  water  is  naturally  heavily  charged  with  undesirable 
salts,  then  the  situation  becomes  as  serious  as  possible. 

When  capital,  therefore,  is  seeking  permanent  investment 
in  the  development  of  an  irrigation  system,  the  difficulties 
pointed  out  are  matters  for  first  and  most  serious  consideration; 
and  when  agriculturists  propose  to  establish  homes  under  such 
surroundings,  the  same  serious  attention  should  be  given  the 
probable  permanency  of  the.  conditions  of  fruitfulness  and  health  - 
fulness. 

It  sometimes  happens  that  water  for  irrigation  must  be  taken 
from  mountain  canons  and  led  out  upon  the  mesas  and  over  the 
valleys  under  great  difficulties,  such  as  tax  the  highest  engi- 
neering skill  to  its  utmost  to  accomplish.  .As  an  illustration  of 
this  type  of  irrigation  engineering,  the  case  of  one  of  the  canals 
supplying  Eedlands,  California,  may  be  cited.  In  Fig.  57  the 
dark  line  on  the  flank  of  the  mountain  on  the  right  is  an  open 
canal,  with  cement  masonry  lining,  which  winds  up  the  valley 
until  it  can  draw  its  supply  from  the  Santa  Ana  river.  Lower 
down  the  mountain  valley  it  becomes  necessary  to  cross  the  canon, 
and  this  is  accomplished  by  using  the  large  redwood  siphon  rep- 
resented in  Figs.  58  and  59.  This  gigantic  pipe  has  an  inside 
diameter  of  4  feet,  and  in  one  portion  of  its  course  is  obliged 


Kedlands   Irrigation    System 


297 


to  withstand  a  pressure  of  160  feet  of  water.  This  pipe  is  made 
of  selected  redwood  staves,  2x6  inches,  with  edges  beveled  to  fit 
closely,  and  having  their  ends  joined  by  a  strip  of  metal  fitting 
tightly  into  a  slot  in  the  end  of  each  stave  ;  the  width  of  the 
metal  strip  being  a  little  greater  than  the  width  of  the  stave, 


Fig.  57.     Santa  Ana  canal  on  mountain  side. 

a  close  joint  is  thus  secured.  The  staves  are  bound  together 
with  iron  hoops,  whose  distance  apart  is  varied  according  to  the 
pressure  the  pipe  is  required  to  withstand. 

When  the  canal  reaches  the  wash  of  Mill  creek,  it  is  carried 
across  in  the  flume  represented  in  Fig.  60,  also  made  of  redwood 
staves.  Further  on,  as  the  water  nears  its  destination,  one 
branch  discharges  its  water  through  the  paved  and  cement- lined 
canal  into  the  paved  and  cement- lined  distributing  reservoir, 
both  shown  in  Fig.  61. 

From  the  reservoir,  the  water  is  taken  in  a  system  of  under- 


Fig.  58.    Redwood  pipe  conveying  water  of  Santa  Ana  canal 
into  and  out  of  a  canon. 


Redwood    Pipe   Line 


299 


ground  cement  pipes  to  the  lands  where  it  is  to  be  used.  These 
pipes  extend  beneath  the  surface,  out  of  sight  and  out  of  the 
way,  ranging  from  14,  12,  10  and  8  inches  in  diameter  for  the 
mains,  to  6  and  5  inches  for  the  laterals  ;  and  there  were  in 
1888  some  13  miles  of  these  pipes  in  the  Redlands  settlement. 

In  the  general  system,  the  lands  are  plotted  in  square 
10-acre  lots,  and  a  5-  or  6-inch  lateral  supplies  one  tier  of  these, 
delivering  the  water  usually  at  the  highest  corner.  These  pipes 


Fig.  59.     Pipe  line  carried  on  trestle. 

are  generally  laid  on  the  slope  of  the  country,  which  one  way 
ranges  from  50  to  100  feet  per  mile,  and  do  not  carry  the  water 
under  much  pressure,  but  rather  more  nearly  as  though  it  wrere 
running  in  open  channels.  The  accumulation  of  pressure  as  the 
face  of  the  country  falls  is  prevented  by  the  introduction  of 
small  concrete  chambers  from  5  to  6  feet  square,  placed  at 
frequent  intervals,  and  at  the  places  of  branching.  As  the  water 
passes  along  the  supply  pipes  it  enters  these  chambers,  rising 
until  it  falls  over  measuring  weirs  in  the  partition  walls  of  the 
chamber,  and  drops  into  other  compartments  from  which  other 
pipes  lead  away  in  their  respective  directions. 


Fig.  60.     Redwood  stave  flume  carried  across  Mill  creek  wash  on  trestle. 


Fig.  61.     CemeuMined  canal  and  reservoir  at  Redlands,  California. 


Distributing   Hydrants 


301 


When  the  water  reaches  the  irrigator,  his  delivery  is  made 
over  a  small  weir,  to  which  the  water  rises  from  below  in  a 
similar  but  smaller  cement  chamber,  two  of  which  are  repre- 
sented in  Figs.  62,  63  and  64.  In  Fig.  62,  the  water  is  seen 
pouring  from  the  cement  chamber  or  "  hydrant "  over  a  small  weir 
into  a  distributing  flume.  Two  other  weirs  in  the  same  hydrant 
are  closed  by  gates,  and  it  will  be  seen  that  by  transferring 
either  of  the  two  gates  to  the  weir  now  in  use,  the  water  would 


Fig.  62.    Cement  hydrant,  with  weir  and  distributing  flume. 

be  turned  from  its  present  course  to  the  one  of  the  other  two 
desired.  In  Fig.  63,  the  water  is  seen  flowing  from  the  front 
weir,  while  the  discharge  is  prevented  from  taking  place  into 
the  compartment  at  the  left  and  in  the  rear  by  the  two  gates 
now  in  place  ;  but  in  Fig.  64,  the  left  gate  has  been  removed 
without  putting  it  in  front,  as  would  ordinarily  be  the  case,  so 
as  to  show  the  water  pouring  over  that  weir  into  its  underground 
pipe  for  delivery  in  another  direction. 

The   system   for  supplying  water   for   irrigation,   now  briefly 
described,  and  illustrated  by  Figs.  57  to  64,  represents  the  high- 


302 


Irrigation  and   Drainage 


est  type  of  collecting  and  distributing  systems  yet  devised,  and 
it  is  one  which  meets  the  peculiar  demands  brought  upon  it  with 
almost  ideal  nicety.  From  the  collecting  reservoir,  up  in  the 
mountains,  behind  the  great  Bear  valley  dam,  the  water  travels 


Fig.  63.     Cement  hydrant,  with  water  discharging  outward 
into  distributing  flume. 

hurriedly  much  of  the  way  through  closed  pipes  of  redwood, 
steel  or  cement,  in  which  all  evaporation  and  seepage  are  effec- 
tually prevented,  while  for  most  of  the  balance  of  the  distance 
the  water  glides  swiftly  along  tight  flumes  and  cement-lined 


Fig.  64.     Same  hydrant  as  Fig.  63,  with  water  discharging 
over  left  weir  into  underground  pipe. 

canals  of  nearly  faultless  alignment,  reaching  its  destination  with 
so  little  of  erosion  or  silting  that  the  annual  expense  for  mainte- 
nance is  almost  a  trifling  matter.  The  dangers  from  alkalies  are 
reduced  to  the  narrowest  possible  margin,  and  the  swamping  of 


304  Irrigation    and    Drainage 

the  land  is  next  to  impossible  with  any  rational  use  of  water. 
When  one  stands  upon  Smiley  Heights,  in  Redlands,  and  looks 
out  over  such  panoramas  of  luxuriant  growth  as  the  one  repre- 
sented in  Fig.  65,  the  reflective  mind  is  almost  convinced  that 
here  is  in  reality  the  ultima  thule  in  rural  life. 

The  cases  now  cited  may  suffice  to  illustrate  the  manner  in 
which  water  is  diverted  from  streams  for  gigantic  irrigation 
enterprises,  where  the  government  itself  does  the  work,  as  ir 
India  ;  where  state  aid  supplements  the  united  efforts  of  a  dis- 
trict, as  in  the  case  of  the  Kern  river  canal,  and  where  one  or 
more  stock  companies  develop  the  system  as  a  means  of  finding 
permanent  investment  for  capital,  as  is  the  case  with  the  system 
worked  out  to  meet  the  needs  of  the  Redlands  district. 

It  is,  of  course,  practicable  for  individuals  to  divert  portions 
of  the  water  from  streams  passing  through  their  property,  pro- 
vided the  fall  is  such  as  to  permit  of  this  being  done,  and 
where  large  quantities  of  water  are  to  be  used  there  is  seldom  a 
cheaper  or  more  effective  method  of  supplying  water,  if  only 
the  land  and  the  stream  are  properly  related  for  it,  and  the 
water  is  not  already  held  by  prior  rights. 

DIVERTING    UNDERGROUND    WATERS 

In  mountainous  and  hilly  .countries,  where  river  valleys  have 
become  deeply  filled  with  sands  and  gravels,  it  frequently  happens 
that  much  of  the  water  of  the  drainage  basin  flows  below  the 
surface  through  the  valley  sands  and  gravels,  the  bed  of  the 
channel  becoming  nearly  or  quite  dry  for  long  distances. 

In  such  cases,  where  the  slope  of  the  valley  is  considerable, 
and  where  the  water  has  not  fallen  too  far  below  the  surface, 
tunnels  are  occasionally  driven  into  the  sands  and  gravels  up 
the  valley  at  a  small  grade  until  the  water-bearing  beds  have 
risen  above  the  line  of  drift  sufficiently  to  allow  the  water  to 
percolate  into  the  tunnel  and  be  led  out  upon  the  surface. 
Sometimes  it  is  only  necessary  to  dig  open  ditches,  making  them 
deeper  up  stream,  to  develop  considerable  quantities  of  water  on 
the  same  principle. 


Diverting    Underground    Waters 


305 


Then,  again,  in  steep  valleys,  where  the  streams  carry  plenty 
of  water,  but  too  far  below  the  surface  to  be  diverted,  it  fre- 
quently happens  that  at  the  foot  of  a  terrace  water  may  be 
flowing  very  near  the  surface  toward  the  river  channel,  and  by 
ditching  or  tunneling  here  this  may  be  diverted  to  the  surface 
when  that  in  the  river  must  be  pumped. 

Another  method  of  utilizing  the  waters  which  have  fallen 
below  the  surface  in  the  valley  gravels  is  by  building  what  is 
called  a  submerged  dam  across  the  valley,  excavating  to  bed 


Fig.  66.    Submerged  dam  at  San  Fernando,  California. 

rock  and  erecting  a  water-tight  dam,  which  shall  hold  the  under- 
flow back  until  it  has  filled  the  gravels  above  the  dam  and  flows 
over  it  at  the  surface  high  enough  to  be  taken  away  in  cement 
ditches,  flumes  or  pipes  to  the  land  it  is  desired  to  irrigate. 
One  such  submerged  dam  is  shown  in  Fig.  66,  built  near  San 
Fernando,  California.  It  was  not,  however,  sufficiently  well  built 
to  hold  the  water  back  until  it  could  be  made  to  overflow,  and 
they  were,  in  1896,  using  two  gasoline  engines  with  pumps  to 
lift  the  water  held  back  by  the  dam,  instead  of  depending  upon 
gravity,  as  planned. 


306  Irrigation   and    Drainage 


DIVERTING    WATER    BY    TIDAL    DAMMING 

Where  lands  bordering  rivers  leading  to  the  sea  lie  high 
enough  above  low  tide  to  admit  of  adequate  drainage,  and  at  the 
same  time  below  high  tide  level,  these  may  be  dyked  off  from 
the  sea,  and  then,  by  erecting  sluices  controlled  by  gates  at 
suitable  places  in  the  dykes,  connecting  with  canals  and  dis- 
tributaries on  the  land  side,  water  may  be  led  at  will  on  or  off 
the  fields  as  the  tides  come  or  go.  One  of  the  most  notable 
examples  of  this  method  of  procuring  water  for  irrigation  is 
at  the  mouth  of  the  Santee  river,  in  South  Carolina,  to  which 
reference  has  already  been  made,  and  a  portion  of  which  is 
represented  in  Fig.  67. 

It  will  be  readily  understood  that  as  the  tide  rises  along  the 
coast,  the  discharge  of  the  fresh  water  coming  down  the  river  is 
prevented  and  the  channels  fill  with  it,  it  being  held  there  by 
the  dam  of  salt  water  formed  by  the  tidal  wave.  When  the 
fresh  water  has  accumulated  to  a  sufficient  extent,  the  trunks 
may  be  opened  and  the  fields  flooded,  or  they  may  be  kept 
closed  and  the  water  held  off.  The  diverting  of  water  from 
rivers  by  tidal  damming  is  only  practicable  where  the  river 
carries  a  sufficient  volume  of  fresh  water  to  prevent  the  salt 
water  from  ascending  the  channel,  for  were  the  volume  small 
the  sea  would  drive  it  back,  and  only  salt  or  brackish  water 
would  be  found  against  the  dykes. 


DIVERTING    WATER    BY    THE    POWER    OF    THE 
STREAM 

Where  rivers  run  too  low  in  their  channels  to  permit 
the  water  being  led  out  directly,  many  devices  have  been 
employed  by  which  a  portion  of  the  water  is  made  to  drive 
machinery  which,  in  turn,  lifts  another  portion  out  upon  the 
land,  where  it  may  be  led  away.  One  of  the  oldest,  commonest 
and  simplest  devices  used  for  this  purpose  is  the  undershot 
water-wheel,  set  up  in  the  stream  and  carrying  buckets  on  its 


Tidal   Irrigation 


307 


Fig.  67.    Section  of  rice  fields  in  South  Carolina. 
(U.  S.  Coast  and  Geodetic  Survey.) 

circumference,  which  raise  the  water  in  the  manner  represented 
in  Fig.  15,  page  76.  This  view  was  taken  on  the  river  Regnitz, 
a  branch  of  the  Main,  in  Bavaria,  where  in  a  distance  of  one 


308  Irrigation   and    Drainage 

and  one-fourth  miles  the  writer  counted  no  less  than  twenty 
such  wheels. 

The  wheels  were  16  feet  in  diameter,  provided  with  a  row 
of  24  churnlike  buckets  on  one  or  both  sides,  emptying  their 
contents  into  a  trough,  from  which  the  water  was  led  away  in 
a  flume  hewn  from  a  log.  At  the  time  the  view  was  taken, 
this  wheel  was  making  three  revolutions  per  minute',  and  dis- 
charging 450  gallons,  or  enough  to  supply  nearly  120  acres  with 
2  inches  of  water  every  10  days,  the  water  being  raised  12  feet. 

On  the  Grand  river,  near  Grand  Junction,  Colorado,  the 
Smith  Brothers  have  placed  two  36 -inch  turbine  wheels  so 
that  they  drive  a  battery  of  two  centrifugal  pumps,  one  above 
the  other,  on  the  same  8-inch  discharge  pipe,  and  lift  water 
82  feet,  discharging  it  into  a  flume,  as  represented  in  Fig.  68, 


Fig.  68.    Mouth  of  8-inch  discharge  pipe  82  feet  above  Grand  river, 
Grand  Junction,  Colorado. 

at  the  rate  of  2,200  gallons  per  minute.  The  two  wheels  were 
together  rated  at  90  horse -power,  and  were  developing  not  far 
from  54,  as  measured  by  the  water  lifted.  They  were  supply- 
ing water  for  80  acres  of  alfalfa  and  120  acres  of  orchards, 
working  only  during  the  daytime,  the  water  being  carried  a 
mile  in  flume  and  ditches. 

Other  forms  of  water  wheels,  like  the  overshot,  undershot 
and  breast  wheels,  are  used  for  driving  centrifugal  and  other 
pumps  to  lift  water  for  irrigation,  and. in  large  streams,  where 


Lifting    Water  by    Water   Power 


309 


be 


there    is    considerable    fall,    large    amounts    of    water    may 
raised  at  a  very  small  cost  after  the  plant  is  once  in  place. 

Mr.  F.  H.  Harvey,  of  Douglas,  Wyoming,  has  set  up  a  half- 
breast  and  undershot  wheel,  10  feet  in  diameter  and  14  feet 
long,  between  two  wing-dams  on  a  swinging  frame,  in  such  a 
manner  as  to  permit  it  to  rise  and  fall  with  the  current.  Being 
connected  by  means  of  a  sprocket  wheel  and  chain  to  the  sta- 
tionary driving  pulley,  the  changes  in  the  position  of  the  wheel 
with  the  level  of  the  river  do  not  disturb  the  action,  "and  the 


Fig.  69.     Hydraulic  ramming  engine.     (Wilson,  U.  S.  Geol.  Survey.) 

device  runs  night  and  day  without  attention,  except  for  oiling, 
pumping  1,000  gallons  per  minute  to  a  height  of  16  feet,  using 
a  3%-inch  centrifugal  pump,  thus  supplying  more  than  50  acre- 
inches  per  day,  or  enough  to  irrigate  200  acres  at  the  rate  of 
2.5  inches  every  10  days.  His  plant  is  described  as  very  effec- 
tive, satisfactory  and,  for  the  amount  of  water  supplied,  cheap, 
the  total  cost  being  $1,200.* 

*Bulletin  No.  18,  Wyoming  Agr.  Exp.  Station. 


310 


Irrigation  and   Drainage 


The  very  large  sizes  of  hydraulic  rams  may  also  be  used 
on  streams  of  relatively  small  fall  for  lifting  water  for  the  irri- 
gation of  small  areas,  especially  if  used  in  connection  with 
reservoirs.  They  are  very  simple,  relatively  cheap,  durable,  and 
require  but  little  attention.  The  ramming  engines,  Fig.  69,  are 
similar  to  the  hydraulic  rams,  but  are  built  larger  and  have 
greater  capacities.  They  are  more  complex  in  structure,  and 
more  expensive.  The  engine  represented  in  the  figure  is  said  to 
be  able  to  elevate  water  to  a  height  of  25  feet  for  every  foot  of 
fall,  or  to  deliver  one-third  of  the  water  used  in  its  operation  at 


Fig.  70.     Siphon  elevator.     (Wilson,  U.  S.  Geol.  Survey.) 

two  and  one-half  times  the  height  of  the  fall,  and  one-sixth  of  the 
water  at  five  times  the  height  of  the  fall.  Those  having  a  drive 
pipe  8  inches  in  diameter  and  a  delivery  pipe  of  4  inches  are 
capable,  under  a  head  of  10  feet,  of  elevating  about  6  acre- inches 
to  a  height  of  25  feet  in  24  hours,  and  this  will  irrigate  24  acres  at 
the  rate  of  2.5  inches  every  10  days.  Such  an  engine  will  cost 
$500  (Wilson). 

The  siphon  elevator,  represented  in  Fig.  70,  is  an  appliance 
utilizing  the  principle  of  the  hydraulic  ram  in  connection  with  a 
siphon.  The  amount  of  water  lifted  by  this  varies  with  the  dimen- 
sions of  the  appliance,  the  height  to  which  the  water  is  lifted,  and 
the  difference  between  the  lengths  of  the  two  legs  of  the  siphon. 
It  can  only  be  used  where  there  is  a  dam,  or  similar  condition, 


Utilizing    Storm    Waters  311 

which  permits  a  considerable    difference  between   the  long   and 
short  legs  of  the  siphon. 

To  start  the  action  of  the  siphon,  the  long  arm  must  be  filled 
with  water ;  then,  as  this  descends  again,  more  water  rises 
through  the  suction  arm  passing  into  the  receiver  (a)  and  through 
the  check-valve  >c)  into  the  regulator  (b).  In  passing  the  check- 
valve,  the  drag  of  the  water  closes  it,  and  thus  stops  the  current  ; 
but  no  sooner  has  this  occurred  than  the  momentum  of  the  water 
opens  the  puppet  valve  (d),  and  a  portion  escapes  into  the 
storage  tank  or  reservoir.  While  the  water  has  been  discharging 
through  the  puppet  valve  and  coming  to  rest,  the  fall  of  water 
in  the  discharge  arm  has  created  a  vacuum  in  the  regulator, 
which  permits  the  atmospheric  pressure  on  the  corrugated  heads 
to  force  them  inward  and  open  the  check-valve,  thus  starting  the 
flow  again.  These  pulsations  are  very  rapid,  ranging  from  150 
to  400  per  minute,  so  that  a  nearly  continuous  flow  is  maintained. 
Wilson  states  that  these  water  elevators  have  been  built  with 
sufficient  capacity  to  deliver  3  acre-feet  in  24  hours,  an  apparatus 
of  this  capacity  costing  $1,200. 


UTILIZING   STORM  WATERS   FOR   IRRIGATION 

There  are  many  sections  of  country  where  the  topography  is 
such  as  to  permit  storm  waters  to  be  caught  by  individual  farmers 
in  reservoirs  formed  by  cheap  earth  dams  thrown  across  the 
axis  of  a  run,  draw  or  ravine,  and  the  floods  produced  by  rains 
held  back  and  used  in  irrigating  lands  below  in  times  of  drought. 
This  is  a  very  common  practice  in  many  parts  of  Europe,  where 
the  collected  waters  are  oftenest  used  on  meadows.  Suitable 
arrangements  are  made  for  taking  out  the  water,  and  a  waste 
weir  is  provided  by  which  the  water  may  escape  before  the  height 
of  the  dam  has  been  reached. 

Where  water  is  supplied  to  large  districts,  the  use  of  dams 
with  reservoirs  is  very  common,  especially  on  streams  which  are 
subject  to  large  fluctuations  in  volume  during  the  irrigation 
season. 


312 


Irrigation  and  Drainage 


Fig.  71.    Exposure  of  windmill  which  during  one  year  pumped  79.1 
acre-feet  of  water  12.85  feet  high. 

It  will  frequently  happen,  also,  that  streams  or  rills  whose 
volume  of.  water  is  too  small  to  be  used  advantageously  may  be 
dammed  and  the  water  accumulated  in  reservoirs,  and  used  by 
single  individuals  ;  or  two,  three  or  more  farmers  may  be  located 
so  as  to  make  it  mutually  desirable  for  them  to  unite  their  efforts 
and  take  advantage  of  small  streams  in  this  way.  So,  too,  may 
the  water  of  springs  be  led  out  to  suitable  places  and  accumulated 
and  warmed  for  use  in  irrigation. 


WIND     POWER     FOR     IRRIGATION 

When  relatively  small  areas  of  land  are  to  be  irrigated  where 
the  lift  is  not  greater  than  10  to  25  feet,  and  where  pumps  may 
be  used  of  such  forms  and  capacity  as  to  economically  utilize  the 
full  power  the  mill  is  capable  of  developing,  wind  power  may  be 
employed  to  good  advantage  in  supplying  water  for  irrigation. 


Wind   Power  for  Irrigation 


313 


"The  writer*  has  conducted  a  series  of  observations  with  a 
16-foot  geared  Aermotor  windmill  during  one  whole  year,  which 
shows  just  how  much  water  was  lifted  12.85  feet  high  each  hour 
of  every  day  under  one  set  of  conditions.  The  amount  of  the 
water  pumped  each  and  every  hour  of  the  day,  and  the  number  of 
miles  of  wind  which  passed  the  mill  and  did  the  work,  were  auto- 
matically recorded,  giving  for  the  first  time  a  complete  record  for  a 
full  year  of  the  amount  of  work  one  windmill  did  in  lifting  water. 
The  mill  stands  on  a  steel  tower  22  feet  above  the  roof  and 
82  feet  above  the  ground,  as  represented  in  Fig.  71,  and  lifted 
the  water  12.85  feet  from  a  reservoir  having  an  area  of  285 
square  feet,  into  a  measuring  tank  holding  141.2  cubic  feet, 
which,  when  filled,  emptied  itself  in  45  seconds  back  into  the 
reservoir.  The  number  of  times  this  measuring  tank  was  filled 
each  hour  of  the  day  during  each  month  of  the  year,  and  the 
miles  of  wind  which  did  the  work,  are  given  in  the  table  on  page 
315,  and  the  results  are  shown  graphically  in  Fig.  72.  In  this 
table  the  numbers  at  the  head  of  the  columns  are  the  hours 


*Bulletin  68,  Wis.  Agr.  Exp.  Station. 


s^ 

4;** 

\ 

/ 

^ 

• 

j 

\ 

/ 

\ 

/ 

\ 

1 

/ 

\ 

• 

/ 

\ 

/ 

\ 

-^ 

/ 

\ 

"^2 

X. 

J7 

s— 

^ 

/ 

x 

^ 

\ 

2 

^ 

^ 

\ 

^- 

\i 

/' 

v_ 



-.  

^ 

~^_ 

too 

i 

Fig.  72.    Upper  curve  shows  miles  of  wind  each  hour  of  the  year.    Lower  curve 
shows  the  number  of  tanks  of  water  pumped  by  the  same  wind. 


314 


Irrigation  and   Drainage 


A  B 

Fig.  73.    Aermotor  14-inch  reciprocating  pump  used  by  windmill. 
A,  pump  ;  B,  piston  head  and  suction  valve. 

of  the  day.  The  lines  of  numbers  opposite  the  name  of  the 
month  express  the  total  number  of  miles  of  wind  for  the  hour 
of  the  day  at  the  head  of  the  column,  while  the  other  lines  ex- 
press the  number  of  times  the  tank  was  emptied  during  each  hour 
of  the  day.  In  the  footings  of  the  table,  the  tipper  line  is  the 
total  number  of  miles  of  wind  during  each  hour  of  the  day  for  the 
full  year ;  the  second  line  is  the  total  number  of  tanks  emptied. 


Table  showing  the  total  number  of  tanks  of  water  pumped  each  hour  of  the  day 
for  each  month,  and  the  total  wind  movement  in  miles  for  the  same  time. 


Month. 

Noon 

1. 

2. 

3. 

4. 

«. 

6. 

7. 

8. 

9. 

10. 

11. 

Mid- 
night 

March.. 

425.0 

446.0 

438.0 

436.5 

411.0 

382.5 

378.5 

,365.5 

332.0 

323.0 

322.0 

2980 

319.0 

113.4 

112.8 

111.8 

101.6 

94.5 

80.1 

61.8 

67.0 

60.3 

46.0 

62.7 

50.1 

50.9 

April  ... 

521.5 

512.5 

476.0 

476.0 

408.0 

436.  5 

392  5 

394.0 

368.0 

424.0 

431.5 

4640 

412.0 

157.0 

153.8 

138.0 

137.2 

126.7 

108.2 

78.7 

74.6 

63.3 

85.8 

103.5 

108.5 

90.3 

May  .... 

446.5 

453.5 

437.0 

4405 

411.5 

361.0 

346.0 

366.5 

378.0 

373.0 

375.0 

367.0 

342.0 

115.6 

122.4 

116.2 

106.3 

93.8 

77.6 

52.7 

66.7 

689 

68.7 

74.5 

72.5 

73.9 

June..  .. 

320.0 

326  5 

310.5 

320.0 

320.0 

305.5 

300.5 

292.5 

299.5 

310.0 

267.5 

267.0 

292.5 

73  4 

78  0 

67.5 

66.2 

61.8 

38,0 

44.0 

48.0 

51.0 

51.0 

38.0 

47.0 

40.0 

July.... 

328.0 

351  .-5 

347.5 

351.5 

325.5 

306.0 

273.0 

253.0 

261.5 

276.5 

258.0 

228.9 

236.5 

75  1 

71.7 

64.5 

67.7 

57.5 

58.2 

34.7 

22.4 

23.5 

26.0 

29.2 

25.7 

29.6 

Aug  

354.0 

352  0 

358.0 

354  0 

326.0 

305.0 

282.0 

255.5 

241.0 

239.0 

247.0 

242.0 

270.5 

76.0 

79.3 

82.9 

75  4 

64.4 

540 

35.0 

35.0 

34.0 

33.0 

34.0 

38.0 

36.0 

Sept  

339.0 

354.0 

362.0 

351.0 

331  :o 

276  0 

246.0 

256.0 

271.0 

264.0 

272.0 

252.0 

251.0 

89.6 

101.6 

96  7 

93,1 

82.1 

49.4 

30.6 

30.3 

37.8 

37.0 

40.3 

38.7 

44.4 

Oct  

392.0 

401.0 

389.0 

376.0 

3590 

318.0 

341.0 

355.0 

342.0 

350  0 

329.0 

314.0 

325.0 

107.2 

114.1 

111  3 

103.9 

96  9 

65.0 

68.4 

83.0 

74  4 

83.3 

82.3 

72.3 

74.5 

Nov  

43(5.0 

443.0 

439.0 

425.0 

388.0 

345  0 

359.0 

373.0 

368.0 

3S5'0 

373.0 

365  0 

371.0 

151.9 

135  0 

139.0 

136.0 

116.0 

112.0 

110.0 

114.0 

110.0 

110.0 

100.0 

94  0 

92.0 

Dec  

395.0 

389.0 

359.0 

331.0 

326.0 

329.0 

334.0 

339.0 

361.0 

359.0 

348.0 

348.0 

364.0 

133.2 

119.8 

102.7 

800 

79.8 

84.3 

89.4 

84.3 

85.2 

83.0 

95.1 

105.0 

101.0 

Jan  

3S8.0 

4090 

37.6.0 

3560 

331.0 

317  0 

352.0 

362.0 

326.0 

334.0 

325.0 

306.0 

330.0 

117.5 

1269 

113.7 

91  5 

79.1 

77.3 

85.2 

86.1 

84.4 

16.6 

71.8 

73.4 

74.1 

Feby.... 

406.0 

412.0 

401.0 

408.0 

381  0 

345.0 

365.0 

365.0 

347.0 

363.0 

368.0 

365  0 

392.0 

119.2 

131  1 

1350 

122.9 

116.4 

103.2 

99.8 

102.6 

100.9 

108.7 

106.3 

109.3- 

115.1 

4741  0 

4850.0 

4693  0 

4625.5 

4318.0 

4026.5 

3969.5 

3977.0 

3885.0 

4000.  B 

3916.0 

3816.9 

3905.5 

1320  1 

1340  5 

1279.3 

1181.8 

1069.0 

907.3 

790.3 

814.0 

793.7 

809.1 

837.7 

834.5 

821.8 

Correc'n 

95.2 

98,5 

92  1 

77  6 

67.1 

53.0 

42.2 

43.6 

45.8 

49.0 

49.8 

49.5 

46.1 

Totals 

1424.3 

1445.0 

1371.4 

1259.4 

1336.1 

960.3 

832.5 

857.6 

839.5 

858.1 

887.5 

884.0 

867.9 

Month. 
March  
April  

1. 

354.5 
64.9 
414.5 
95.1 
334.5 
75.4 
269.0 
.  36.0 
220.0 
27.3 
232.0 
26.0 
263.0 
44  1 
316.0 
72.4 
3720 
102.Q 
378.0 
102.0 
350,^; 
784 
405  0 
117.1 

2. 

3. 

4. 

347.0 
56.9 
410.5 
87.6 
347.5 
77.5 
261.5 
20.4 
208.0 
18.0 
273.0 
42.2 
255.0 
61.4 
284.0 
55.0 
408.0 
96.0 
352.0 
91.6 
325.0 
70.0 
397.0 
952 

5. 

433.0 
53.3 
404.0 
84.8 
353.5 
78.8 
269.0 
35.0 
218.0 
21.9 
259.0 
31.0 
254.0 
45.2 
265.0 
45.7 
408.0 
95.0 
330.0 
85.9 
3390 
70.0 
384.0 
92.3 

G. 

7. 

8. 

383.5 
74.0 
410.0 
124.8 
397.0 
104.8 
322.5 
80.0 
258.0 
37.1 
269.0 
48.0 
258.0 
53.9 
312.0 
66.9 
424.0 
129.0 
340.0 
94.1 
365.0 
96.2 
373.0 
112.7 

9. 

410.0 
85.1 
488.5 
139.4 
409.5 
1024 
310.0 
63.0 
2860 
47.9 
289.5 
57.0 
289.0 
62.8 
318.0 
72.8 
448.0 
142.9 
349.0 
99.0 
384.0 
95.1 
390.0 
118.6 

1O. 

11. 

Totals. 

8765.0 
1777.4 
10417.0 
2648.5 
9472.0 
2035.6 
7149.0 
1242.7 
6112.0 
973.0 
6702.0 
1150.8 
6591.0 
1378.5 
7934.0 
1869.4 
9303.0 
2822.3 
8557.0 
2331.5 
8474.0 
2112.7 
91200 
264'6.2 

344.0 
54.9 
410.0 
89.7 
3'24.5 
68.8 
278.5 
29.0 
215.5 
27.0 
220.5 
30.0 
265.5 
45.0 
309.0 
69.2 
388.0 
107.0 
377.0 
104.5 
354.0 
76.7 
3960 
107.9 

89~9 
329.5 
65.6 
275.5 
27.4 
211.0 
18.9 
243.5 
37.2 
249.5 
43.4 
307.0 
66.1 
412.0 
102.0 
372.0 
1030 
334..  0 
76.6 
419.0 
106.5 

331.0 
64.8 
429.5 
92.6 
356.0 
76.5 
281.0 
63.0 
227.0 
27.7 
275.0 
36.0 
261.0 
52.8 
288.0 
57.3 
416.0 
108.0 
358.0 
99.9 
348.0 
83.8 
3830 
97.8 

363.5 
75.1 
453.5 
120.2 
389.5 
89.6 
353.5 
76.0 
247.5 
37.3 
239.0 
44.0 
2660 
49.8 
273.0 
47.5 
416.0 
1260 
338.0 
83.0 
335.0 
95.7 
384.0 
112.1 

427.0 
95.3 
493.5 
148.0 
435.5 
96.4 
291.5 
58.0 
311.0 
60.1 
306.5 
62.0 
310.0 
73.4 
351.0 
89.5 
4340 
148.9 
370.0 
115.2 
389.0 
111.5 
382.0 
115.5 

388.0 
84.4 
4750 
150.8 
410.0 
89.4 
297.0 
51.0 
319.5 
64.0 
298.0 
60.4 
301.0 
75.1 
349.0 
90.4 
438.0 
145.6 
380.0 
110.5 
374.0 
100.5 
348.0 
100.0 

May 

June  
July  

August  
Sept  

Oct  

Nov  

Dec 

Jan 

Eeby  , 

Correction*.. 
Totals  

0908.5 
840.7 
50.8 

3882.5 
809.7 
47.1 

31)130 
792  3 
44.1 

3868.5 
772.4 
4-1.6 

3916.5 
738.9 
40.2 

3953.5 
860.2 
52.6 

4058.5 
956.3 
63.5 

4112.0 
1021.5 
66.6 

1088.1 

4371.5 
1086.0 
72.3 

4501.0 
1173.8 

82.8 

4377.5 
1122.1 
73.9 

98905.0' 
22988.0 

891.5 

856.8 

836.4 

814  0 

'779.1 

9128 

1019.8 

1158.3 

12566 

1196.0 

24433.0 

*Approximate  correction  for  water  pumped  during  the  time  the  tank  was  being 
emptied, 


316 


Irrigation  and   Drainage 


The  total  water  pumped  during  the  year  by  this  windmill 
enough  to  cover  79.1  acres  12  inches  deep,  thus  showing  an 
average  daily  rate  of  2.6  acre -inches.  The 
largest  amount  of  water  pumped  on  any 
single  day  was  39,540.2  cubic  feet,  or  a  rate 
for  24  hours  of  27.46  cubic  feet  per  min- 
ute. There  were  short  times  occasionally, 
however,  when  more  water  than  this  was 
pumped,  but  the  capacity  of  the  siphon 
was  such  as  to  cause  it  then  to  discharge 
continuously,  and  thus  prevent  a  record  be- 
ing made. 

Most  of    the    water  was  lifted   by    two 
pumps,  working  singly    or    in    combination. 
These  were  an  Aermotor  14-inch  reciprocat- 
ing pump,  worked  on  a  9-inch  stroke,  repre- 
sented  in  Fig.  73,  and  a  Seaman  &  Schuske 
bucket   pump,    with    1 -gallon    buckets,     as 
represented    in    Fig.   74.     When    the    wind 
was    light   the    mill  was    given    the   bucket 
pump,    when     stronger     the     reciprocating 
pump,  and  when  strongest  both  pumps    at 
Fig.  74.    Bucket  irriga-    the    same    time,   and   more    work   was    ac- 
tion pump,  complished  in    this  way  than    would    have 
been  possible  with  any  single  pump. 


WATER   PUMPED    DURING   10-DAY   PERIODS 

Since  the  availability  of  wind  power  for  irrigation  is  limited 
not  so  much  by  the  total  work  of  the  year  as  by  the  water 
which  may  be  pumped  in  times  of  special  need,  a  clearer  idea 
of  the  possibilities  of  wind  power  for  irrigation  can  be  gained 
by  tabulating  the  work  done  during  the  year  by  10-day  periods. 
This  has  been  done  in  the  table  which  follows,-  but  first  reducing 
the  results  to  a  lift  of  10  feet  instead  of  12.85  feet,  the  height 
the  water  was  actually  raised  ; 


Wind   Power  for  Irrigation 


317 


Table  showing  computed  amount  of  water  lifted  10  feet  high  during  consecutive 
10-day  periods  for  one  full  year,  expressed  in  acre-inches 


DATE 

Water 
pumped 

DATE 

Water 
pumped 

DATE 

Water 
pumped 

Feb  28-Mch    10 

Acre-in. 
33  540 

July  8-18 

Acre-in. 
21  53 

Nov   15-25 

Acre-in  . 

52  77 

Mch    10-20 

36  620 

July  18-28     

29.73 

Nov.  25-Dec.  5  .  . 

47  46 

Mch.  20-30  
Mch.  30-Apr.  9  
Apr  9-19 

52.77 
47.01 
54  11 

July  28-Aug.  7  .  . 
Aug.  7-17  
Aug  17-27 

9.87 
36.26 
20  20 

Dec.  5-15  
Dec.  15-25  
Dec  25-  Jan  4... 

39.52 
31.18 
51  22 

Apr  19-29 

63  05 

Aug.  27-Sept.6.. 

21.27 

Jan.  4-14  

33.92 

Apr  29—  M.ay  9 

59  97 

Sept.  6-16  

18.00 

Jan   14-24  

29.16 

May  9-19 

28  69 

Sept.  16-26  

40.42 

Jan.  24-Feb.  3... 

59.36 

May  19-29  
May  29-June8  
June  8-18 

51.38 
40.54 
27  59 

Sept.  26-Oct.  6.. 
Oct.  6-16  
Oct.  16-26  

23.79 
55.07 
18.45 

Feb.  3-13  
Feb.  13-23  
Feb.  23-28  

33.45 
75.73 
16.20 

June  18-28  
June  28-  July  8 

13.82 
26.68 

Oct.  26-Nov.  5.  .  . 
Nov.  5-15  

36.71 
49.49 

Referring  to  the  table,  it  will  be  seen  that  the  smallest 
amount  of  water  pumped  in  any  10  days  was  9.87  acre-inches, 
this  occurring  between  July  28  and  August  7,  at  a  time  when 
most  water  is  needed.  In  this  period  there  were  7  full  days 
when  no  water  was  pumped,  all  the  water  being  raised  during 
3  days  of  the  period. 

The  mean  amount  of  water  'pumped  during  the  100  days 
from  May  29  to  September  6  was  24.5  acre-inches  per  10  days, 
and  as  this  is  the  season  in  the  United  States  when  most  water 
is  needed  for  irrigation,  the  figure  may  be  taken  as  representing 
the  capacity  of  such  a  pumping  system.  That  is  to  say,  such  a 
plant  is  able  to  supply  10  inches  of  water  to  24.5  acres  during 
100  days  when  the  lift  is  10  feet,  and  to  12.25  acres  where  the 
lift  is  20  feet.  If  the  crop  irrigated  demands  20  inches  of  water 
in  100  days,  then  the  area  which  could  be  supplied  under  a 
10-foot  lift  would  be  only  12.25  acres,  and  under  a  20-foot  lift 
only  6.12  acres.  It  must  be  understood,  however,  that  these 
results  are  possible  only  under  conditions  of  no  loss  between  the 
pump  and  the  land  to  which  the  water  is  applied. 

From  theoretical  considerations  and  the  above  data,  it 
appears  probable  that  for  different  sizes  of  wheels  and  for  dif- 
ferent lifts,  but  under  otherwise  similar  conditions,  areas  may 
be  irrigated  as  given  in  the  table  below. 


318  Irrigation  and  Drainage 

Number  of  acres  a  first-class  windmill  may  irrigate  to  a  depth  of  10  inches 


Diam.  of 
wheel 

8.5  ft. 
10  ft. 
12  ft. 
14  ft. 
16  ft. 

Lift  10 
10  ins.  per 
100  days 

2.40 
7.58 
m  13.61 
"  17.44 
24.50 

and  20 

feet 
20  ins.  per 
100  days 

1.20 
3.79 
6.81 
8.77 
12.25 

inches  in  100  days 

Lift  15  feet 
10  ins.  per     20  ins.  per 
100  days         100  days 

1.60                  .80 
5.06                 2.53 
9.08                 4.54 
11.70                 5.85 
16.34                 8.17 

Lift 
10  ins.  per 
100  days 

1.20 
3.79 
6.81 
8.77 
12.25 

20  feet 
20  ins.  per 
100  days 

.60 
1.90 
3.40 
4.39 
6.13 

In  computing  this  table  for  other  sizes  of  wheels,  we  have 
used  the  ratios  calculated  by  Wolff  ;  *  but  as  our  observed  work 
is  about  12  per  cent  less  for  the  16 -foot  wheel  than  he  com- 
putes for  this  size,  the  values  in  the  table  are  correspondingly 
lower  than  his  table  would  give.  It  is  the  writer's  conviction, 
however,  that  the  results  he  has  observed  for  the  16-foot 
wheel  are  quite  as  high  as  will  be  likely  to  be  realized  by 
average  practice  with  the  pumping  devices  of  to-day. 


NECESSARY  CONDITIONS   FOB   THE   HIGHEST   SERVICE 
WITH   A   WINDMILL 

In  order  that  the  largest  service  may  be  secured  from  a 
windmill,  there  are  certain  essential  conditions  which  must  be 
observed.  First  among  these  is  a  good  wind  exposure.  It  is 
useless  to  purchase  a  windmill  and  then  set  it  up  in  such  a 
manner  that  the  wind  cannot  have  free  access  to  it.  Strong 
towers,  having  a  height  of  70  to  90  feet,  should  usually  be 
used,  and  these  placed  where  hills,  groves  or  other  obstructions 
cannot  break  the  force  of  the  wind. 

Second  in  importance  to  a  good  exposure  of  the  mill  is  a 
pumping  outfit  thoroughly  adapted  to  the  power  of  the  mill.  It 
should  not  be  so  heavy  as  to  force  the  mill  to  stand  idle  in  winds 
of  9  miles  per  hour,  and  yet  it  should  be  capable  of  utilizing 
the  full  power  developed  in  a  25-  to  30-mile  wind. 

*A.  R.  Wolff,  the  Windmill  as  a  Prime  Mover. 


Wind  Power  for  Irrigation  319 

If  reciprocating  pumps  are  used,  the  strokes  should  be  made 
as  long  as  possible  and  the  number  not  higher  than  20  to  25 
per  minute,  to  avoid  loss  of  energy  in  pounding.  Suction  and 
discharge  pipes  should,  as  a  rule,  be  as  large  as  the  cylinder, 
and  where  water  is  to  be  raised  above  the  surface,  this  should 
be  done  by  carrying  the  discharge  pipe  up  into  the  tower  to 
the  necessary  height  to  avoid  the  use  of  stuffing  boxes.  The 
large  wooden  plunger  rods,  which  displace  one -half  the  volume 
of  the  water  raised  with  each  stroke,  are  in  the  direction  of 
economy  in  making  the  pump  in  a  measure  double-acting.  If 
a  screen  must  be  used  over  the  end  of  the  suction  pipe,  it  should 
be  given  large  capacity,  and  be  carefully  watched,  to  see  that 
it  does  not  become  clogged.  All  valves  should  have  large 
ports,  easy  action,  and  be  tight  fitting,  so  that  every  stroke, 
whetner  slow  or  quick,  shall  discharge  the  full  capacity  of  the 
cylinder. 

There  should  be  two  pumps  of  different  capacities,  so  arranged 
that  either  may  be  used  alone,  or  the  two  used  at  once,  thus 
providing  three  loads,  to  be  applied  when  the  wind  is  light, 
medium  or  strong.  This  can  readily  be  arranged  by  attaching 
the  lighter  pump  directly  to  the  mill  and  the  larger  one  to  a 
walking-beam  ;  or  both  may  be  attached  to  a  walking-beam, 
T>ne  end  of  which  is  carried  by  the  driving  rod  of  the  mill. 

The  geared  windmills  may  readily  be  made  to  work  a  pump 
of  the  bucket  type,  Fig.  74,  and  if  the  buckets  can  be  provided 
with  valves  which  do  not  leak,  a  pump  of  large  size  may 
be  used,  speeded  back  so  as  to  be  driven  by  the  mill  in  the  lighter 
winds,  and  with  increasing  speed  in  the  higher  winds,  without 
reaching  the  limit  at  which  the  buckets  fail  to  empty. 

But  as  the  power  of  the  mill  increases  more  rapidly  than 
the  velocity  of  the  wind,  what  is  needed  is  a  device  which 
is  capable  of  increasing  the  load  more  rapidly  also*  Attaching 
an  additional  pump  secures  this  end,  but  the  objection  to  the 
plan  is  that  it  is  not  automatic,  and  much  service  must  be  lost 
by  the  mill  being  either  too  heavily  or  too  lightly  loaded  until 
an  attendant  can  make  the  change.  Still,  this  plan  is  worth 
following  until  something  better  can  be  had. 


320  Irrigation  and   Drainage 


THE    USE    OP    RESERVOIRS 

To  employ  wind  power  for  irrigation  to  the  best  advantage, 
a  reservoir  is  required  in  most  cases.  There  are  localities  on 
the  seashore  where  nearly  every  day  a  sufficient  breeze  springs 
up  to  drive  the  windmill,  and  in  such  cases,  if  the  supply  of 
water  is  large,  the  lift  small,  and  the  demand  for  water  moder- 
erate,  the  ground  for  many  crops  may  be  laid  out  in  such  a 
manner  that  a  system  of  rotation  may  be  followed,  and  the 
reservoir  dispensed  with  ;  but  in  such  cases  the  time  and 
attention  required  for  the  distribution  of  the  water  will  usually 
be  greater  than  where  a  reservoir  is  used. 

The  reservoir  should  be  placed  where  it  is  high  enough  to 
serve  all  the  ground  to  which  it  is  desired  to  supply  water,  but 
it  is  very  important  to  keep  it  just  as  low  as  possible,  because 
since  the  economic  lift  of  the  mill  is  only  10  to  25  feet,  every 
foot  saved  on  the  height  of  the  lift  into  the  reservoir  is  a  large 
percentage  gained  in  efficiency.  The  elevated  wooden  tanks, 
placed  on  towers  far  above  the  ground  to  be  irrigated,  are  very 
expensive  in  themselves,  and  greatly  reduce  the  area  which  a 
windmill  can  irrigate. 

In  constructing  a  reservoir  where  soil  and  subsoil  are 
reasonably  fine  and  close,  the  first  step  is  to  remove  from  the 
area  all  rubbish  and  coarse  litter  that  may  interfere  with  the 
close  packing  of  the  soil.  The  land  upon  which  the  walls  of  the 
reservoir  are  to  be  built  is  then  plowed,  leaving  a  dead  furrow 
in  the  center,  which  may  be  filled  with  water  until  the  whole 
area  is  thoroughly  saturated.  When  the  water  has  drained 
away  sufficiently  to  permit  of  teams  driving  over  the  ground, 
the  soil  should  be  thoroughly  trampled  and  puddled,  after  which 
dirt  from  the  bottom  of  the  reservoir  may  be  scraped  on  and 
trampled  with  the  teams  continuously  and  thoroughly.  It  is 
recommended  as  an  excellent  plan  to  maintain  the  sides  of  the 
walls  higher  than  the  center,  but  all  portions  nearly  enough 
horizontal,  so  that  water  may  be  pumped  into  the  furrow  at 
night,  to  help  in  settling  the  materials  more  closely  and  render 
the  puddling  more  complete. 


The    Use   of  Reservoirs  321 

After  the  walls  have  been  raised  to  the  proper  height,  the 
bottom  of  the  reservoir  is  plowed,  harrowed  fine,  and  the  whole 
flooded  with  water,  if  practicable,  to  better  fit  the  soil  for 
puddling.  In  case  the  soil  is  at  first  too  open  for  flooding  all 
at  once,  the  water  may  be  led  in  furrows  close  together,  filling 
as  many  at  a  time  as  the  capacity  of  the  pump  will  permit, 
turning  the  water  into  others  when  a  sufficient  saturation  has 
been  reached.  When  the  bottom  of  the  reservoir  has  been 
thoroughly  puddled  over  the  whole  area  and  continuous  with  the 
puddled  bottom  and  sides  of  the  walls,  there  will  usually  be  but 
little  loss  from  seepage. 

The  sluice  for  taking  out  water  for  irrigation  should  be  laid 
in  the  wall  at  the  level  of  the  ditch  outside  which  carries  the 
water  to  the  fields  or  garden,  but  at  some  distance  above  the 
bottom  inside,  so  that  the  water  may  not  be  entirely  withdrawn 
and  permit  the  sun  to  dry  the  soil,  thus  destroying  the  effect  of 
puddling.  In  cold  climates,  it  is  also  important  to  retain  enough 
water  in  the  reservoir  to  prevent  the  bottom  from  freezing,  as 
this  may  destroy  the  effect  of  puddling. 

The  sluice  should  project  entirely  through  the  walls  on  both 
sides,  and  be  provided  with  a  suitable  gate  or  valve  for  closing 
and  opening  it,  either  fully  or  only  in  part,  according  to  the 
amount  of  water  needed,  and  the  dimensions  should  be  such  as  to 
permit  more  water  to  be  taken  out  than  is  likely  to  be  needed. 

The  most  thoroughly  satisfactory  and  permanent  outlet  for 
a  reservoir  can  be  provided  by  using  wrought  iron  pipe  of  suit- 
able size,  provided  with  an  elbow  at  the  inside,  which  opens 
upward.  This  may  be  closed  by  means  of  a  plug  worked  by  a 
T  lever  or  handle,  keeping  the  threads  well  protected  with 
cylinder  or  wagon  grease,  to  prevent  rusting  in. 

Oftener  the  sluice  is  made  of  2 -inch  plank,  tightly  put 
together  and  provided  with  a  gate,  as  represented  in  Fig.  75*. 
In  other  cases,  the  mouth  of  the  sluice  is  cut  off  obliquely,  and 
a  gate  is  hinged  to  the  upper  side  and  provided  with  a  handle 
reaching  above  water,  to  which  a  cord  is  attached  for  opening 

*From  Bulletin  No.  55,  Kansas  Agr.  Exp.  Station. 
U 


322 


Irrigation  and   Drainage 


the  gate  by  simply  pulling  upon  it.  This  is  very  simple  and 
easily  operated.  In  placing  the  sluice  in  the  wall  of  the  reser- 
voir, great  care  is  needed  to  get  the  dirt  thoroughly  tamped  and 
puddled  about  it,  so  that  water  shall  not  follow  its  sides  and 
develop  a  leak. 

To    prevent    injury  from  waves,  the  walls    of   the    reservoir 
should  be  sloping  and  no.t  steeper  inside  than  a  rise  of  1  in  2. 


Fig.  75.     Sluice  and  gate  for  reservoir.     (Kansas  Agr.  Exp.  Station.) 

At  the  outlet  ditch  there  should  be  provided  an  overflow  weir 
sufficiently  below  the  top  of  the  wall  to  prevent  wave  action 
from  starting  a  cut  in  the  top  by  breaking  over.  A  reservoir, 
completed  and  filled  with  water,  is  represented  in  Fig.  76, 
but  where  these  are  made  circular  in  form  there  must  be  less 
seepage  through  the  banks  in  proportion  to  the  amount  of  water 
stored,  because  less  wall  is  required  to  enclose  a  given  area 
when  this  is  circular. 


The    Use  of  Reservoirs 


323 


The  amount  of  seepage  from  reservoirs  must  vary  with  the 
character  of  the  soil,  but  Carpenter  cites  a  case  where  the  loss 
from  this  cause  did  not  exceed  2  feet  for  a  whole  year,  and 
this  is  satisfactorily  small. 

Where  the  soil  is  very  open  and  sandy,  it  may  be  necessary 
to  haul  on  clay  or  fine  soil  to  use  in  puddling,  or  the  reservoir 
may  require  covering  with  coal  tar,  asphalt  or  cement.  These 


I 


Fig.  76.    Rectangular  reservoir  for  windmill  irrigation. 

materials,  however,  are  expensive,  and  usually  not  within  the 
reach  of  small  irrigators. 

The  loss  of  water  from  a  reservoir  by  evaporation  in  dry, 
windy  climates  is  much  larger  than  the  necessary  seepage,  and 
this  can  only  be  lessened  by  planting  windbreaks  about  the 
reservoir. 

A  circular  reservoir  4  feet  deep  and  40  feet  in  diameter  will 
supply  .35  acres  with  4  inches,  and  .69  acres  with  2  inches  of 
water.  One,  100  feet  in  diameter  and  4  feet  deep  will  irrigate 
4.32  acres  with  2  inches  of  water  and  2.16  acres  with  4  inches, 
while  a  reservoir  209  feet  on  a  side  and  4  feet  deep  will  supply 
water  enough  to  irrigate  12  acres  with  4  inches  of  water,  16 
acres  with  3  inches,  and  24  acres  with  2  inches. 


324 


Irrigation  and   Drainage 


PUMPING    WATER    WITH    ENGINES 


The  amount  of  water  which  was  pumped  by  a  16-foot  geared 
windmill  with  a  lift  of  12.85  feet  has  been  given  as  79.1  acre- 
feet  as  the  work  of  a  year. 

A  2%"  horse -power  Webster  gas  engine  was  used  on  the  same 
pumps  with  which  the  windmill  did  most  of  its  work,  and  with 
the  same  lift,  to  see  what  amount  of  water  could  be  supplied  by 
such  a  power.  During  a  6-hours'  run  the  engine  lifted  13,202.2 
cubic  feet  12.85  feet  high,  with  a  consumption  of  458  cubic  feet 
of  gas  costing  $1.25  per  thousand,  or  at  a  rate  of  95.4  cents  per 

day  of  10  hours. 

At  this  rate  of  pumping  and  cost 
for  fuel,  the  engine  could  supply  in 
100  days  50.67  acres  with  12  inches 
of  water  at  a  cost  for  fuel  of  $95.40 
or  $1.88  per  acre  for  the  season,  and 
$3.76  where  24  acre -inches  of  water 
is  applied. 

On  our  own  place  the  same  make 
and  size  of  engine  as  that  used  above, 
and  represented  in  Fig.  77,  but  using 
gasoline  at  9  cents  per  gallon  for 
fuel,  and  lifting  the  water  against  a 
head  of  50  feet  with  a  double-acting 
pump,  discharging  75  gallons  per 
minute,  the  cost  for  a  96 -hours'  run 
iwas  $4.95. 

The  water  pumped  in  this  time 
was  432,000  gallons  at  the  rate  of 
$1  for  3.214  acre-inches.  In  100 
days  of  10  hours  this  plant  would 
lift,  under  its  conditions,  601,605  cubic  feet  of  water,  or  13.81 
acre-feet,  at  .a  cost  fcr  fuel  of  $51.56,  thus  making  the  experse 
$3.73  for  12  inches  in  depth  of  water  per  acre,  and  $7.46  for  24 
inches. 


Fig.  77.    Webster  2%  horse-power 
vertical  gasoline  engine. 


..«•    -<•  ••-S^^i.-5-.f. —t-^ 
•  ">*-«?^«>-'»<.    -• 

Fig.  78.    Persian  wheel  for  lifting  water.     (Wilson,  U.  S.  Geol.  Survey.) 


Fig.  79.    Bucket  pump  for  use  with  horse  power.     (Wilson,  U.  S.  Geol.  Survey.) 


326  Irrigation  and   Drainage 

Such  a  pumping  plant  as  this  would  easily  irrigate  10  acres 
12  inches  deep  and  5  acres  24  inches  deep  without  the  aid 
of  a  reservoir,  and  with  the  aid  of  a  reservoir  the  area  could 
be  made  15  acres  or  7.5  acres,  according  to  amount  of  water 
used. 

For  the  field  irrigation  on  the  Wisconsin  Agricultural  Experi- 
ment Station  farm,  we  have  used  an  8-horse-power  portable 
steam  engine  driving  a  No.  4  centrifugal  pump.  Soft  coal  at 
$4  per  ton  has  been  used  for  fuel,  and  with  a  lift  of  26  feet, 
drawing  the  water  through  110  feet  of  6 -inch  suction  pipe  and 
discharging  it  through  varying  lengths  of  the  same  pipe  up  to 
.1,200  feet,  the  coal  consumed  has  been  at  the  rate  of  one 
ton  for  an  average  of  80,210  cubic  feet,  or  22.1  acre-inches. 

At  the  above  rate  the  fuel  cost  of  an  acre -inch  of  water  is 
18.1  cents,  making  12  inches  of  water  amount  to  $2.17  per  acre, 
and  24  inches  $4.34  as  the  cost  for  fuel. 

Willcocks  states  that  taking  the  mean  of  some  60  observa- 
tions carefully  made  in  the  delta  and  Upper  Egypt,  the  actual 
discharge  obtained  for  a  4-meter  lift  is  480  cubic  meters  per 
horse-power  per  12  hours,  taking  the  8-horse-power  engine  as 
the  standard,  and  he  italicizes  this  statement  :  "A  discharge  of 
480  cubic  meters  per  nominal  Jwrse-poicer  per  12  hours  is  the  mean 
in  Egypt." 

He  also  estimates  the  cost  of  working  a  10-horse-power 
engine  in  the  interior  of  Egypt  as  follows  : 

£  $ 

Driver  and   stoker,  per  day 15  .73 

Oil,  etc.,  per  day 05  .24 

Coal,  away  from  canals  per  day 1.00        4.84 

^|~5  of    10  per  cent  per  annum  on  cost  of  engine, 

for  depreciation,  repairs,  etc 10  .48 

Total £1.30       $6.29 

The  amount  of  water  pumped  by  the  10-horse-power  engine 
to  a  height  of  13.12  feet  is  3.891  acre-feet,  which  from  the 
above  table  makes  the  cost  per  acre -foot  $1.62  where  the  ground 
is  covered  to  a  depth  of  12  inches,  and  $3.24  per  acre  where 
the  depth  is  made  24  inches. 


Methods   of  Pumping 


327 


Fig.  80.     Shadoof  of  Egypt,  or  Paecottah  of  India.     (Wilson, 
TJ.  S.  Geol.  Survey.) 

Taking  an  average  8-hour  day  for  pumping,  the  above 
pumping  plant  should  irrigate  during  a  100 -day  season  259.4 
acres  to  a  depth  of  12  inches  and  129.7  acres  to  a  depth  of 
24  inches,  at  a  total  cost  for  pumping  of  $420.23. 


328 


Irrigation  and  Drainage 


THE    USE    OF    ANIMAL    POWER    FOR    LIFTING   WATER 
FOR    IRRIGATION 

Many  and  very  old  are  some  of  the  devices  invented  to 
utilize  both  human  strength  and  that  of  cattle  and  horses. 
Fig.  78  represents  the  Persian  wheel,  very  extensively  used  in 
Asia  Minor  and  in  Egypt  for  lifting  water,  two  cattle  raising 
as  much  as  2,000  cubic  feet  per  day  on  low  lifts.  A  more 


Fig.  81.    Doon  of  India.     (Wilson,  U.  S.  Geol.  Survey.) 


modern  device  is  represented  in  Fig.  79,  where  one  horse  may 
elevate  through  a  height  of  20  feet  500  cubic  feet  of  water  per 
hour  and  5,000  per  day  of  10  hours,  or  a  rate  which,  if  followed 
for  100  days,  would  give  more  than  11  acres  12  inches  of  water 
in  depth. 

Much  land  is  irrigated  in  India,  Asia  Minor  and  Egypt, 
where  the  water  is  lifted  by  man -power,  and  Figs.  80  and  81 
show  two  of  the  forms  of  lifting  devices  upon  which  men  are 
worked.  Two  men,  working  alternately,  are  said  to  irrigate  an 
acre  in  3  days  with  the  shadoof,  lifting  the  water  about  4  to  6 
feet. 


CHAPTER    X 

METHODS   OF  APPLYING   WATER  IN  IRRIGATION 

WHEN  water  has  been  provided  for  irrigation  and 
brought  to  the  field  where  it  is  to  be  applied,  the 
steps  which  still  remain  to  be  taken  are  far  the  most 
important  of  any  in  the  whole  enterprise,  not  except- 
ing those  of  engineering,  however  great,  which  may 
have  been  necessary  in  providing  a  water  supply 
which  shall  be  constant,  ample  and  moderate  in  cost ; 
for  failure  in  the  application  of  water  to  the  crop 
means  utter  ruin  for  all  that  has  gone  before. 

To  handle  water  on  a  given  field  so  that  it  shall 
be  applied  at  the  right  time,  in  the  right  amount, 
without  unnecessarily  washing  or  puddling  the  soil  or 
injuring  the  crop,  requires  an  intimate  acquaintance 
with  the  conditions,  good  judgment,  close  observation, 
skillful  manipulation,  and  patience,  after  the  field  has 
been  put  into  excellent  shape ;  and  right  here  is 
where  a  thorough  understanding  of  the  principles 
governing  the  wetting,  puddling  and  washing  of  soils, 
and  possible  injury  to  crops  as  a  result  of  irrigation, 
becomes  a  matter  of  the  greatest  moment.  There  is 
great  need  of  more  exact  scientific  knowledge  than  we 
now  have  to  guide  the  irrigator  in  his  handling  of 
water. 

(329) 


330  Irrigation  and  Drainage 

PRINCIPLES    GOVERNING    THE    WETTING    OP    SOILS 

When  water  is  applied  to  a  soil  which  becomes 
more  open  in  texture  and  coarser  grained  as  the  depth 
below  the  surface  increases,  it  will  travel  downward 
in  nearly  straight  lines,  and  will  spread  laterally  but 
very  little  except  by  the  relatively  slow  process  of* 
capillarity.  This  fact  is  forcibly  illustrated  in  Fig. 
82,  where  the  experiment  consisted  in  maintaining  the 
level  of  the  w^ater  in  a  hole  at  the  place  designated  by 
the  arrow  until  200  cubic  feet  had  percolated  into  the 
soil.  The  heavily  shaded  area  in  the  figure  shows 
the  mass  of  soil  completely  filled  with  water  on  the 
two  dates,  October  15  and  17,  while  the  water  was 
running.  It  will  be  seen  that  although  the  hole  was 
kept  full  and  the  water-level  within  8  inches  of;  the 
surface,  the  water  did  not  spread  sideways  more  than 
2.5  feet  until  below  a  depth  of  11  feet. 

If  we  imagine  this  to  represent  a  cross -section  of 
the  soil  under  a  water -furrow  extending  across  a 
field,  it  will  be  readily  seen  how  much  water  would 
be  lost  by  rapid  percolation  directly  downward,  and 
how  little,  even  after  a  long  time,  would  have  spread 
laterally  to  wet  the  field.  To  irrigate  such  soils  satis- 
factorily and  economically,  the  water  must  be  spread 
over  the  whole  surface,  or  be  led  in  furrows  which 
are  near  together  across  the  field,  so  that  the  soil 
between  the  furrows  may  quickly  become  wet. 

While  the  water  is  in  the  furrows,  it  will  travel 
sideways  by  capillarity  fastest  in  those  soils  which  are 
coarsest,  for  the  same  reason  that  it  flows  downward 


Principles   of   Wetting   Soil 


331 


fastest ;  namely,  because  the  pores  are  largest  and 
offer  less  resistance  to  the  flow.  The  truth  of  this 
statement  will  be  readily  apprehended  by  studying 
Fig.  83,  which  shows  how  greatly  the  diameter  of  the 


Fig.  82.    Slow  rate  of  lateral  spread  of  water  in  soil. 

waterways  in  a  soil  is  modified  by  the  size  and  ar- 
rangement of  the  soil  grains.  This  being  true,  it  is 
plain  that  water  should  be  moved  most  rapidly  over 
the  coarsest  soils,  in  order  that  unnecessary  waste  by 
deep  percolation  may  not  take  place. 


332 


Irrigation   and    Drainage 


If  a  soil  decreases  in  fineness  of  texture  as  the 
depth  increases,  then  there  may  be  a  considerable 
lateral  spreading  of  the  water  due  to  gravity,  and 


Fig.  83.    Size  and  arrangement  of  soil  grains  as  influencing  pore  space 
and  capillary  waterways. 

this,  aided  by  capillarity,  will  permit  the  furrows  to 
be  placed  farther  apart  and  the  water  to  be  run  more 
slowly  over  the  ground. 

Where  a  fine,  loamy  soil  is  underlaid  at  3  to  5  feet 
with  a  subsoil  of  much  finer  texture,  through  which 
the  water  percolates  slowly,  then  water  may  be  led 
quite  rapidly  through  furrows  some  distance  apart  and 
considerable  quantities  applied  at  once,  depending 
upon  it  to  spread  laterally  by  gravity,  and  to  rise  by 
capillarity  under  the  spaces  between  the  furrows,  in 
this  way  wetting  the  larger  part  of  the  soil  of  the 


Principles   of   Wetting   Soil  333 

field  by  a  sort  of  sub -irrigation,  which  should  be 
utilized  to  the  fullest  extent  possible,  for  then  the 
intervals  between  irrigations  may  be  longest  and  the 
duty  of  water  will  be  highest. 

If  the  soil  is  allowed  to  become  very  dry  before 
watering,  especially  if  the  texture  is  close  and  the 
grains  fine,  water  will  percolate  downward  less 
rapidly,  and  it  will  move  sideways  and  rise  under  the 
influence  of  capillarity  more  slowly,  because  the  air  of 
the  soil  must  be  displaced  ahead  of  the  water. 

A  fine  soil,  flooded  under  these  conditions,  will 
take  water  very  slowly,  because  the  surface  pores  be- 
come filled  with  water,  which  is  retained  with  so 
much  force  that  air  bubbles  cannot  readily  rise  through 
it,  and  the  conditions  are  similar  to  a  jug  filled  with 
air  bottom  upwards  under  water, —  the  one  cannot 
escape  nor  the  other  enter.  Such  soils,  therefore, 
which  must  be  flooded  should  not  be  allowed  to  reach 
this  dry  condition.  The  case  is  not  so  bad  when 
furrow -irrigation  is  practiced,  because  the  water  pres- 
sure in  the  furrow  may  displace  the  air  laterally 
where  it  can  escape  upward  between  the  furrows 
unhindered  by  the  water. 

On  the  other  hand,  there  are  conditions  when  it  is 
desirable  to  take  advantage  of  this  hindrance  of  air 
to  percolation.  Where  a  clover,  alfalfa,  grass  or  grain 
field  must  be  watered  by  flooding,  and  where  the  head 
of  water  is  small,  the  fall  slight,  and  the  distances 
the  water  must  be  led  long,  the  spreading  will  be 
much  more  rapid  and  better  when  the  surface  soil  has 
become  dry.  Indeed  we  have  repeatedly  tried  to 


334  Irrigation   and    Drainage 

water  a  certain  piece  of  land  when  the  surface  soil 
was  yet  quite  moist,  and  found  it  impossible  to  do  so 
with  the  available  head,  because  the  water  would  sink 
into  the  ground  faster  than  it  could  be  supplied ;  but 
by  letting  the  soil  become  dryer  the  same  head  spread 
the  water  easily  over  the  whole  area,  wetting  it 
evenly,  though  there  was  greater  hindrance  from  the 
clover  having  become  thicker  and  larger. 

In  furrow  irrigation,  the  same  principle  may  be 
taken  advantage  of  in  cases  where  the  rows  are  long 
and  the  head  of  water  too  small,  though  not  to  the 
same  extent ;  but  the  difference  is  sufficiently  pro- 
nounced to  be  sometimes  quite  helpful  in  open  soils. 

PRINCIPLES    GOVERNING    THE    PUDDLING    OF    SOILS 

A  puddled  soil  is  one  in  which  the  compound  soil 
kernels  or  crumbs  have  been  broken  down  more  or 
less  completely  into  separate  grains  and  run  together 
^into  a  closely  compacted  mass.  Such  a  soil  may  hold 
its  pores  between  the  grains  so  completely  filled  with 
water  until  lost  by  evaporation  that  little  free  air 
is  present  except  that  absorbed  in  the  water  itself.  In 
such  a  soil  roots  quickly  suffer  for  lack  of  air,  the 
process  of  nitrification  cannot  go  on,  and,  what  is 
even  worse,  the  nitrates  already  present  in  the  soil 
when  the  puddling  occurred  may  be  rapidly  lost  by 
the  process  of  denitrification. 

The  water -logging  of  a  soil  has  the  same  dis- 
astrous effects  regarding  the  roots  of  plants  and  on 
the  processes  of  nitrification  and  denitrification.  Both 


The   Puddling   of  Soils  335 

conditions  should,  therefore,  be  studiously  avoided  by 
every  irrigator. 

If  soils  to  be  irrigated  contain  black  alkali,  and 
this  has  been  permitted  to  accumulate  at  the  surface 
during  the  interval  between  waterings,  it  is  evident 
that  the  flooding  of  such  soils  will  redissolve  the 
alkali,  and  as  this,  in  solution,  tends  of  itself  to  pro- 
duce puddling,  it  is  evident  that  the  irrigation  of 
such  lands  should  always  be  done  with  the  greatest 
care,  in  order  not  to  complicate  the  difficulties  of  the 
crop  by  adding  that  of  a  puddled  soil  to  the  dele- 
terious action  of  the  carbonate  of  soda. 

It  is  extremely  difficult  to  completely  submerge 
a  recently  stirred  soil  of  any  kind  without  breaking 
down  the  crumb  structure  so  essential  to  perfect  tilth, 
and  all  are  familiar  with  the  fact  that  there  is  no 
way  to  so  effectually  compact  loose  soil  in  a  trench 
as  to  completely  fill  it  with  water.  It  is,  therefore, 
plain  that  soils  should  be  watered  before  plowing 
and  fitting,  when  the  running  together  cannot  take 
place,  rather  than  after  the  ground  is  seeded.  Indeed, 
water  enough  should  always  be  present  in  a  soil  at 
seeding  time,  not  only  to  germinate  the  crop,  but  to 
carry  it  well  on  in  growth,  so  that  if  baking  of  the 
soil  must  take  place,  less  harm  will  be  done.  There 
are  few  soils  which  it  would  be  safe  to  flood  just 
after  a  crop  like  oats,  wheat  or  barley  is  up,  for  fear 
of  packing  the  soil  and  seriously  injuring  the  crop. 

When  the  plants  have  attained  some  size,  when 
the  soil  has  gained  in  firmness  by  the  natural  pro- 
cesses of  settling,  and  when  the  roots  have  spread 


336  Irrigation   and    Drainage 

and  occupied  the  soil,  the  shading,  the  firming  and 
the  root  binding  all  conspire  to  prevent  puddling 
and  baking,  so  that  flooding  may  then  be  practiced 
with  less  danger  of  harm  ;  and  so  grass  lands,  alfalfa 
and  clover  may  always  be  flooded  with  little  danger 
of  injuring  the  texture  of  t'he  soil,  because  the  exten- 
sive root  systems  prevent  it. 

When  water  is  applied  in  furrows  without  wash- 
ing, so  that  it  rises  and  spreads  through  the  soil 
between  the  furrows  by  capillarity,  it  then  has  the 
opposite  effect  from  puddling,  and  tends  rather  to 
improve  the  texture  by  drawing  the  loosened  soil 
grains  together  into  clusters  by  an  action  of  surface 
tension  like  that  which  rolls  drops  of  water  into  spheres 
on  a  dusty  floor.  As  the  soil  crumbs  become  satu- 
rated with  capillary  water  the  loose  dust  particles  which 
have  been  formed  in  tilling  are  drawn  to  them  and 
bound  closely  by  the  pull  of  the  surface  film ;  but 
so  soon  as  the  whole  soil  becomes  immersed  in  water, 
as  in  the  case  of  flooding,  and  as  happens  in  the  bottoms 
of  the  furrows,  there  is  then  no  surface  tension,  and 
the  soil  grains  fall  apart  under  the  water  of  their  own 
weight,  and  compacting  and  puddling  are  the  results. 

It  follows,  therefore,  that  all  crops  where  the 
ground  is  not  covered  by  them,  and. where  cultivation 
is  resorted  to  to  prevent  loss  of  water  by  evaporation, 
should  so  far  as  practicable  be  irrigated  by  the  fur- 
row method ;  and  since  the  bottoms  of  the  furrows 
must  be  subjected  to  the  conditions  which  puddle, 
it  follows  that  the  furrows  should  always  be  as  far 
apart  as  other  conditions  will  permit. 


The    Washing   of  Soils  337 

PRINCIPLES    GOVERNING    THE    WASHING    OF    SOILS 

One  of  the  commonest  mistakes  of  beginners  in 
irrigation  is  the  use  of  too  large  volumes  of  water 
in  a  place  and  hurrying  it  over  the  ground  too 
rapidly.  It  must  be  kept  ever  in  mind,  in  all  sorts 
of  irrigation,  that  the  eroding  and  transporting  power 
of  water  increases  with  the  velocity  with  which  it 
moves,  but  in  a  higher  ratio ;  to  double  the  rate  at 
which  water  moves  in  a  furrow  or  over  the  surface, 
increases  its  power  to  wash  and  carry  the  soil  for- 
ward nearly  fourfold. 

In  good  irrigation,  the  water  is  forced  to  move 
so  gently  that  it  runs  nearly  or  quite  clear  and  with- 
out washing  the  sides  or  bottom  of  the  furrows,  and 
if  one  does  not  succeed  in  securing  flows  without 
washing,  the  only  conclusion  which  should  be  drawn 
is  that  the  right  way  has  not  yet  been  learned,  not 
that  it  cannot  be  done. 

Naturally,  the  steeper  the  slope  of  the  furrows 
the  faster  the  water  tends  to  run.  So,  too,  when  the 
slope  remains  the  same,  the  larger  the  volume  of  water 
in  the  furrow  the  faster  the  water  will  flow,  and  these 
two  principles  give  the  irrigator  nearly  complete  con- 
trol of  the  situation. 

If  the  ground  is  flat  and  the  water  moves  too 
slowly,  increase  the  amount  in  the  furrow,  and  if 
there  is  not  water  enough  to  do  this,  decrease  the 
number  of  furrows  handled  at  one  time.  If  the  water 
runs  too  fast  and  washes,  divide  up  the  stream,  lead- 
ing it  into  more  furrows  until  the  movement  comes 


338  Irrigation   and    Drainage 

to  be  the  rate  which  does  not  wash  or  erode.  We 
have  seen  orchards  in  the  foothills  of  California  irri- 
gated by  carrying  the  water 'in  furrows  down  the  hill 
where  the  slopes  were  too  great  to  readily  plow  with 
a  team  and  yet  it  was  done  with  such  skill  that  no 
appreciable  wash  was  produced,  neither  did  any  water 
run  to  waste.  Everything  was  adjusted  with  such 
nicety  that  by  the  time  the  streams  had  reached  the 
ends  of  the  furrows  the  whole  of  the  water  had  been 
absorbed  by  the  soil.  The  30  acres  referred  to  were 
owned  and  managed  by  a  Swede,  and  when  he  was 
asked  if  he  did  not  find  it  difficult  to  handle  the  water 
so  as  not  to  wash  his  soil  and  waste  the  water  on 
these  steep  hills,  with  no  grading  or  terracing,  the 
reply  was  :  "  Easy  now  ;  but  was  very  hard  when  I 
didn't  know." 

The  most  essential  point  in  the  distribution  of 
water  is  to  have  the  furrows  on  a  nearly  uniform 
slope,  so  that  the  velocity  of  flow  will  be  closely 
uniform  through  their  entire  length.  If  the  same 
grade  cannot  be  secured  throughout,  it  is  better  to 
change  from  a  steeper  slope  to  one  more  flat  than 
the  reverse,  because  then  the  reduction  in  velocity 
will  be  partly  made  up  by  a  greater  depth  of  water 
in  the  furrow  on  the  flatter  reaches. 

FIELD    IRRIGATION    BY    FLOODING 

When  large  areas  of  land  are  to  be  irrigated  in 
single  blocks,  there  is  no  method  of  applying  water 
which  is  so  economical  of  labor  and  of  time  as  the 


340  Irrigation   and    Drainage 

systems  of  flooding,  whenever  it  is  possible  to  estab- 
lish and  maintain  the  best  conditions  for  them,  and 
there  is  no  other  system  which  permits  of  so  uni- 
form a  wetting  of  the  surface. 

There  are  two  fundamentally  different  systems  of 
flooding.  One  covers  the  surface  of  a  field  with  a 
thin  sheet  of  running  water,  maintained  until  the 
desired  saturation  has  been  reached ;  the  other  covers 
the  surface  with  a  sheet  of  standing  water,  which  is 
allowed  to  remain  until  the  soil  has  absorbed  enough, 
when  the  balance  is  drawn  off  ;  or,  simply  as  much 
water  as  is  desired  is  placed  upon  the  land,  and  this 
remains  on  the  surface  until  it  is  absorbed. 

The  two  systems  are  used  most  for  crops  like 
the  small  grains,  grasses  and  clovers,  which  closely 
cover  the  ground,  and  where  intertillage  is  not  practiced. 
They  are  also  used  extensively  where  fields  for  any  crop 
must  be  moistened  preparatory  to  plowing  and  seeding. 

Flooding  by  running  water  is  practiced  with  great 
nicety  and  thoroughness  on  large  fields  of  40,  80  and 
even  160  acres  in  the  old  Union  Colony  at  Greeley, 
Colorado.  Here,  usually,  the  natural  slope  of  the 
country  is  good,  and  a  distributing  ditch  is  carried 
along  the  highest  edge  of  a  field  to  be  irrigated. 
When  the  time  for  watering  has  arrived,  the  field  is 
divided  into  lands  of  60  to  120  feet  by  parallel  fur- 
rows, made  by  using  a  wide  V-shaped  plow,  throwing 
the  earth  both  ways,  thus  forming  distributing  fur- 
rows, represented  in  Fig.  84,  about  30  inches  wide  at 
the  top.  These  furrows  are  made  rapidly  with  a  3- 
or  4 -horse  team,  and  when  a  crop  of  grain  is  ready 


Field   Irrigation   by   Flooding  341 

to  cut,  a  common  plow  is  driven  up  one  side,  and 
down  the  other  of  the  furrow,  thus  filling  it  and 
leaving  the  field  in  shape  to  be  driven  over  with  the 
harvesting  machine.  The  ridge  of  earth  on  each  side 
of  the  distributing  furrow  serves  the  purpose  of 


Fig.  85.     Canvas  dam  taken  up. 

borders  to  the  lands,  which  prevent  the  return  of 
the  water  to  the  furrows  after  it  has  been  thrown 
out  by  the  dam,  shown  at  the  point  where  the  man 
stands  in  the  cut. 

This  dam  is  simply  a  piece  of  canvas  tacked  by 
one  edge  to  a  strip  of  wood  2x4  inches  in  thick- 
ness and  6  or  8  feet  long,  as  seen  in  Fig.  85. 


342  Irrigation   and    Drainage 

When  in  use,  it  is  laid  in  the  furrow  with  the  canvas 
up  stream  and  the  free  edge  loaded  with  earth  to 
hold  it  down,  when  it  effectually  holds  back  the  water 
and  throws  it  out  upon  the  strip  to  be  watered. 

Water  is  turned  into  one,  two,  three  or  more  of 
these  distributing  furrows  from  the  head  ditch, 
according  to  the  amount  available,  and  when  the 
lands  have  become  sufficiently  wet  as  far  below  the 
canvas  dams  as  the  water  will  readily  flow  through 
the  grain  or  grass,  these  are  picked  up  and  moved 
farther  down  and  the  stream  again  turned  out. 
Water  is  thus  led  over  successive  lands  until  the 
whole  field  has  been  irrigated  easily,  rapidly,  cheaply 
and,  at  the  same  time,  well. 

Where  crops  are  grown  in  short  rotation  on  a 
large  scale,  as  they  are  at  Greeley,  wheat,  alfalfa  or 
clover  and  potatoes  following  one  another  in  regular 
order,  it  is  doubtful  if  a  better  or  more  satisfactory 
system  of  irrigation  can  be  devised  than  the  one 
described. 

If  the  slopes  of  the  field  are  steep,  and  especially 
if  they  incline  in  various  directions,  then  the  small 
grains  and  grasses  may  sometimes  be  irrigated  better 
by  the  method  represented  in  Fig.  86,  where  water  - 
furrows  are  thrown  across  the  surface  of  the  slope 
nearly  along  contour  lines,  giving  them  only  so  much 
fall  as  is  needed  to  lead  the  water  forward. 

These  furrows  for  grain  fields,  where  they  are  tem- 
porary, would  be  best  formed  with  the  ordinary  plow, 
at  the  time  of  seeding,  and  the  upturned  earth 
smoothed  down,  so  that  it  may  become  set  before  the 


Field   Irrigation   ~by   Flooding 


343 


water   must  be   led   across    it.      Where  help  is  scarce 
and  the  price  of  the  crop  small,  it  is  often  the  prac- 
tice  to   enter   the   field  with  the   plow  just  before  the 
water  is  to  be  applied,  and  form  the  furrows  then. 
In   watering   by  this   method,  the  aim  is  to  throw 


Section  2ZF 


Fig.  86.    Flooding  field  on  steep  slopes.     (Grunsky.) 

the  water  over  the  lower  edge  of  the  furrow  in  a 
continuous  sheet  or  else  at  short  intervals,  to  flow 
down  the  slope  until  the  portion  of  the  field  within 
reach  has  received  what  is  needed.  To  do  this, 
canvas  dams  or  temporary  earth  dams  are  used,  as 


344  Irrigation   and    Drainage 

described  above  ;  then,  when  the  water  is  to  be  carried 
forward,  the  dams  are  also  shifted 

As  represented  in  the  figure,  water  may  be  carried 
directly  down  the  slope  across  a  series  of  secondary 
furrows,  as  at  C,  D,  D,  D,  and  the  main  supply  fur- 
rows may  be  set  one  below  another  at  such  intervals 
as  the  extent  of  the  fields  and  the  slope  of  the 
surface  may  demand.  In  the  figure,  a  second  water 
furrow  is  marked  "supply  and  drain  ditch,"  but  if 
the  best  work  is  done  in  handling  the  water,  there 
should  be  no  surplus  to  drain  away. 

When  slopes  like  those  under  consideration  are 
in  permanent  meadows  or  pastures,  or  if  they  are  in 
meadows  for  three  or  more  years,  it  will  be  best 
usually  to  give  more  time  to  shaping  the  furrows, 
so  that  washing  will  not  occur  when  less  attention 
is  given,  and  so  that  the  mower  and  horse  rake  may 
readily  work  over  and  across  them. 

In  European  countries,  where  so  much  labor  is 
done  by  hand,  little  attention  has  been  paid  to 
developing  systems  of  applying  water  to  fields  which 
will  readily  permit  of  the  use  of  machinery,  as  must 
be  the  case  in  this  country,  at  least  for  a  long  time 
to  come. 

Where  grain  fields  are  not  very  long,  and  where 
the  slope  is  gentle  and  uniform,  the  water  may  be 
distributed  from  a  single  head  ditch  by  simply  mark- 
ing the  field,  after  it  has  been  sowed,  with  a  tool 
like  the  corn -marker,  but  having  runners  close  enough 
to  give  shallow  furrows  every  15  or  20  inches. 
These  shallow  furrows  lead  the  water  forward  in  par- 


Field   Irrigation   by   Hooding  345 

allel  lines  from  which  the  lateral  spread  may  be,  to 
a  large  extent,  by  capillary  creeping,  and  they  guide 
the  flow  past  minor  inequalities,  preventing  the  water 
from  becoming  concentrated  so  as  to  do  injury 
through  increase  in  volume  and  velocity  and  from 
running  around  areas,  leaving  them  dry.  This  mark- 
ing is  so  rapidly  and  cheaply  done,  and  obstructs 
the  surface  so  little,  that  it  is  to  be  highly  recom- 
mended where  applicable. 

A  corrugated  roller  might  be  used  instead  of  the 
sliding  marker  to  form  the  water  lines,  but  this 
would  have  no  tendency  to  throw  the  kernels  of  grain 
to  one  side,  and  the  channels  would  be  more  obstructed 
by  the  plants.  Neither  could  so  great  a  depth  be 
secured,  especially  on  heavy  soils  not  deeply  and 
recently  worked. 

In  the  second  flooding  system,  where  the  water  is 
made  to  stand  over  the  whole  surface  to  any  desired 
depth,  the  fields  must  be  laid  out  in  areas  bounded  by 
ridges  or  low  levees,  which  check  -  the  flow  of  water 
and  hold  it  as  in  a  wide  and  extremely  shallow 
reservoir. 

The  size  of  the  checks  in  which  a  field  is  laid  out 
will  be  determined  by  its  general  slope,  by  the  head 
of  water  available,  and  by  the  height  of  the  levees  or 
check  ridges.  It  is  desirable,  for  meadow  and  grain 
irrigation,  to  make  the  checks  as  large  as  practicable 
and  at  the  same  time  to  keep  the  ridges  so  low 
as  not  to  interfere  with  the  movement  of  farm 
machinery  over  the  field. 

If  the   slope  of  the   field  is   6  inches  in  200  feet, 


346  Irrigation   and    Drainage 

and  it  is  desired  to  place  the  upper  edge  of  each 
check  under  2  inches  of  water,  it  would  be  neces- 
sary to  construct  the  levees,  for  checks  200  feet 
square,  about  10  or  12  inches  high,  because  the  water 
would  be  8  inches  deep  on  the  lower  edge  when  the 
surface  was  covered  2  inches  at  the  higher  side,  and 
a  margin  of  2  to  4  inches  is  needed  for  safety 
against  the  water  breaking  across  over  slight  depres- 
sions or  against  wave  action. 

If  the  fields  are  to  be  used  continuously  for  mead- 
ows, pastures,  alfalfa,  or  either  of  these,  in  rotation 
with  small  grains  or  similar  crops  which  may  be  best 
irrigated  by  flooding,  it  will  usually  be  desirable  to 
make  the  check  ridges  broad  and  flat,  so  that  mowers 
and  harvesters  and  even  plows  may  readily  move  over 
them.  They  thus  become  permanent  features  of  the 
field.  If  a  20-,  40-  or  80-acre  field  is  to  be  laid  off 
in  regular  checks,  this  would  probably  be  most  rapidly 
and  cheaply  done  by  a  system  of  plowing  in  repeated 
back -furrows  until  the  desired  height  of  ridges  is 
reached.  The  sizes  of  the  checks  would  first  be  deter- 
mined, and  then  all  the  ridges  extending  in  one 
direction  formed,  first  at  the  distance  apart  found 
desirable,  after  which  the  field  would  be  crossed  in 
the  other  direction,  forming  in  the  same  manner  the 
other  sides  of  the  checks. 

In  cases  where  a  single  plowing  does  not  give 
sufficient  height  to  the  ridges,  and  in  countries 
where  the  rainfall  is  sufficient  to  permit  moderate 
crops  to  be  grown  without  irrigation,  the  labor  of 
fitting  the  ground  in  this  way  may  be  made  a  part 


Field   Irrigation   by   Flooding  347 

of  the  regular  plowing  for  the  crops,  and  permitted 
to  extend  through  a  number  of  years,  thus  making 
the  expense  of  fitting  the  ground  for  irrigation 
mainly  that  of  fitting  the  land  for  crops.  By  this 
plan  the  field  would  be  plowed  in  lands  in  one  direc- 
tion, with  the  back  furrows  always  in  the  same  place, 
until  the  desired  height  is  attained ;  then  these  back 
furrows  would  be  crossed  to  form  the  other  sides  of 
the  checks,  plowing  in  the  same  manner. 

In  case  the  checks  are  large,  the  land  between 
the  ridges  may  be  subdivided  and  plowed  in  the 
ordinary  way,  letting  the  back  furrows  and  dead 
furrows  alternate  in  position  with  the  seasons,  in  the 
usual  manner.  There  will  be  some  finishing  work 
required,  especially  where  the  check  ridges  cross  one 
another. 

It  is  not,  of  course,  necessary  that  the  flooding 
checks  shall  be  square.  If  the  field  has  a  consider- 
able fall  in  one  direction  and  little  or  none  in  the. 
other,  the  checks  may  be  made  much  longer  in  the 
nearly  level  direction,  and  thus  reduce  the  labor  and 
inequalities  in  the  field. 

In  cases  where  the  slopes  are  more  or  less  undu- 
lating, the  check  ridges  which  are  horizontal  will 
necessarily  follow  the  course  of  contour  lines,  and 
may  neither  cross  the  others  at  right  angles  nor  be 
parallel  with  one  another,  but  they  may  still  be 
formed  in  the  same  manner. 

When  it  comes  to  flooding,  the  water  may  be 
taken  from  the  head  distributary  and  sent  down  first 
one  tier  of  checks  and  then  another,  dropping  the 


348  Irrigation   and    Drainage 

water  from  the  first  into  the  second  and  the  second 
into  the  third,  over  one  or  more  breaks  or  weirs  in 
the  dividing  check  ridges.  If,  however,  the  checks 
are  large  or  very  many,  this  plan  will  be  unneces- 
sarily wasteful  of  water,  and  a  better  plan  is  to  take 
the  water  down  the  crest  between  two  lines  of  checks 
in  a  secondary  furrow.  From  this  furrow  the  water 
may  be  turned  into  the  check  on  one  side  and  then 
on  the  other,  flooding  by  pairs  down  the  whole  line. 

In  the  San  Joaquin  valley  of  California,  in  Kern 
county,  there  is  laid  out  one  of  the  largest  flooding 
systems  in  the  world.  Here  are  more  than  30,000 
acres  of  alfalfa  in  a  single  solid  block.  The  slope  of 
the  country  ranges  from  5  feet,  to  the  mile  to  less 
than  2.  Large  volumes  of  water  are  at  the  command 
of  the  company, —  30  cubic  feet  per  .second, —  and  so 
the  checks,  laid  out  with  their  level  ridges  on  contour 
lines,  have  various  sizes  and  many  shapes.  The 
largest  checks  contain  200  acres,  while  the  average  is 
about  40.  The  ridges  are  12  to  20  inches  high,  with 
a  maximum  width  at  the  base  of  12  to  18  feet, 
broadl}*  rounded,  and  all  covered  with  the  growing 
alfalfa. 

Where  the  period  of  rotation  is  short,  and  where 
crops  not  suited  to  flooding  are  used  in  the  rotation, 
then  narrower  and  temporary  check  ridges  would  be 
formed  for  the  crops  to  be  watered  in  this  way.  The 
smallest  ridges  may  be  rapidly  made  on  recently 
plowed  fields  by  using  a  V-shaped  ridging  scraper 
drawn  by  horses,  with  the  open  side  forward.  The 
spreading  wings  throw  the  loose  earth  into  the  angle, 


C  1  D 

^^^^^^JS^^^^^^^^^^SSB^^^^^^^^^S^^^ 


Fig.  87.    Flooding  field  by  rectangular  cheeks.     (Grunsky.) 


-••f. ;- 


•     .1 

r f 1 


"•t 


Fig.  88.    Flooding  field  by  contour  checks.     (Grunsky.) 


350  Irrigation    and    Drainage 

where  it  is  dropped  in  a  continuous  ridge,  because  a 
portion  of  each  plank  is  cut  away  at  the  vertex,  thus 
leaving  an  opening  which  passes  over  the  gathered  earth. 
If  larger  ridges  are  desired,  a  wider  scraper,  with  wide 
opening  in  the  rear,  may  be  followed  by  one  of 
smaller  dimensions,  to  complete  the  gathering. 

The  mounted  road  grader  may  be  used  to  advan- 
tage in  forming  such  ridges,  and  it  would  be  an  easy 
matter  to  construct  a  special  tool  for  this  purpose  on 


Fig.  89.    Model  of  flooding  by  checks. 

the  principle  of  the  road  grader,  but  having  two 
scrapers  instead  of  one,  mounted  in  such  manner  that 
they  could  be  set  closer  together  or  farther  apart,  as 
desired. 

After  the  earth  has  been  gathered  into  ridges,  this 
may  be  smoothed  down  and  rounded  with  a  light 
harrow,  followed  by  a  roller,  if  greater  firmness  is 
desired.  In  Figs.  87,  88  and  89  are  different  forms 
of  flooding  checks,  showing  how  the  water  may  be 
handled  in  them. 


Fitting   the    Surface  for   Irrigation  351 

PITTING    THE    SURFACE    FOR    IRRIGATION 

Whichever  system  of  flooding  or  other  irrigation  is 
used,  it  is  very  important  that  the  smaller  inequalities 
of  the  surface  should  be  removed  by  some  method  of 
grading,  in  order  that  the  water  may  spread  uni- 
formly, wetting  the  whole  area.  If  this  leveling  is 
not  done,  some  portions  of  the  field  will  receive  too 
much  water  while  other  areas  will  receive  too  little  or 
none  at  all,  and  hence  yields  far  below  the  maximum 
will  be  the  result. 

Various  forms  of  leveling  devices  are  in  use,  and 
Fig.  90  represents  one  of  the  best,  made  specially  for 
this  purpose,  and  an  ordinary  road  grader  would  un- 
questionably form  an  excellent  tool  for  doing  this 
work. 

There  are  many  forms  of    scrapers  of   simple  con- 
struction  which  are    improvised  on  the  farm  to   meet 
the  needs  of  the  moment.     One  of  these  is  a  letter  A 
form,  made  of  two  2x12- 
inch  plank,  put  together 
so  as  to  stand  on  edge 
and  be  drawn  over  the 
ground     weighted    with 
the  driver   riding  upon 
it.     The  lower  edges  of 
the  plank  may  be  shod 
with  strips  of    steel   or 
band  iron,  and  thus  made  more  durable  and  effective. 

Another  form  is  represented  in  Fig.  91,  and  con- 
sists of  two  side  runners  held  together  by  cross-bars 


352 


Irrigation   and    Drainage 


of  strong  plank,  set  at  an  angle  and  shod  with  steel, 
as  shown.  This  tool  is  much  used  in  France  and 
Italy,  and  a  modification  of  it  we  saw  in  use  at 
Grand  Junction,  Colorado,  where  a  pair  of  low  wheels 


Fig.  91.     Simple  land  grader. 


u 


were  attached  to  the  front  of  the  scraper  on  a  bent 
iron  axle,  which  could  be  worked  by  means  of  a  lever 
to  raise  or  lower  the  scraper  at  will,  thus  causing  it 
to  drop  or  take  on  dirt  where  desired. 


FIELD    IRRIGATION     BY    FURROWS 

Where  crops  like  maize,  sorghum  and  potatoes  are 
grown  in  large  fields,  and  where  intertillage  must  be 
practiced,  it  is  usually  best  to  irrigate  by  the  furrow 
method  after  the  crop  is  on  the  ground.  In  countries 


Meld    Irrigation   by    Furrows  353 

where  the  soil  must  be  prepared  for  planting  by  first 
watering,  it  is  very  important,  especially  with  pota- 
toes, that  the  soil  should  be  thoroughly  saturated  to  a 
depth  of  4  feet  before  fitting  the  ground. 

If  these  crops  are  to  follow  clover  or  alfalfa,  as 
will  usually  be  the  case,  the  preliminary  watering  may 
be  given  in  the  late  winter  or  early  spring  by  one  of 
the  flooding  methods,  if  the  ground  has  been  fitted  for 
that ;  but  however  the  saturation  is  accomplished,  the 
soil  should  have  all  it  will  carry  at  the  time  of  fitting 
for  seed,  unless  natural  rainfall  may  be  depended 
upon. 

After  planting,  frequent  surface  tillage  to  conserve 
the  moisture  should  be  practiced,  and  the  crop  carried 
forward  as  far  as  possible  without  irrigation.  The 
harrow  should  follow  the  planter  at  once  for  both 
maize  and  potatoes,  and  frequently  thereafter  as  long 
as  the  crop  will  bear  it  without  injury,  which  will  be 
after  both  are  well  out  of  the  ground. 

Where  a  vigorous  growth  of  vines  can  be  main- 
tained by  intertillage  alone  until  they  cover  the 
ground  and  the  tubers  begin  to  set,  this  is  by  far  the 
best  practice  for  potatoes.  So,  too,  is  it  best  for 
nearly  all  crops  planted  in  rows  which  permit  of  cul- 
tivation ;  and  it  should  ever  be  kept  in  mind  that 
4  feet  of  good  soil  well  saturated  and  well  cared  for 
by  intertillage  may  easily  carry  6  and  even  8  inches 
of  available  water,  and  this,  under  good  conditions, 
is  far  more  effective  than  any  which  may  be  ap- 
plied later. 

When   potatoes   are   ready  to    be   laid    by,  the    last 


354  Irrigation   and    Drainage 

cultivation  should  be  with  a  double -wing  cultivator, 
which  will  form  a  furrow  midway  between  the  rows 
and  at  the  same  time  throw  the  soil  up  under  the 
vines,  forming  a  high,  broad  ridge  of  mellow  soil 
above  the  roots  in  which  the  tubers  may  set  and  over 
which  the  water  should  never  rise.  The  furrows  thus 
formed  fit  the  field  for  irrigation. 

When  the  time  for  irrigation  has  arrived,  which 
should  be  deferred  as  long  as  the  vines  continue  to 
grow  vigorously,  water  will  be  taken  from  the  head 
ditch  and  subdivided  between  as  many  rows  as  it  will 
supply,  as  represented  in  Figs.  92,  93  and  94,  where 
the  first  one  shows  the  canvas  dam  just  put  in  place 
in  a  head  ditch  in  a  field  near  Greeley,  Colorado. 
Fig.  93  shows  the  irrigator,  with  rubber  boots  and 
spade,  opening  the  head  ditch  to  let  tJfae  water  into 
the  furrows  ;  while  Fig.  94  shows  the  water  30  minutes 
later,  as  it  is  flowing  between  rows  40  rods  long. 

It  will  be  noted  that  the  water  has  been  let  into 
only  alternate  rows,  and  this  is  a  common  practice 
where  water  is  scarce.  It  is  also  a  frequent  practice 
where  water  must  be  taken  in  rotation  and  the  time 
is  too  short  to  go  over  the  whole  field.  In  such 
cases,  when  the  next  turn  comes  the  water  would  be 
sent  down  the  remaining  rows. 

Very  great  care  is  taken  not  to  let  in  so  much 
water  as  to  fill  the  furrows  and  flood  the  hills,  for 
:t  is  far  better  to  let  the  water  rise  under  the  hills 
by  capillarity.  • 

In  another  field  near  the  same  city,  two  men  were 
irrigating  47  acres  of  potatoes  planted  in  rows  120 


Fig.  92.    Canvas  dam  in  place,  preparatory  to  turning  water  into 
potato  rows  of  Fig.  94. 


Pig.  93.     Opening  head  ditch  of  Fig.  92,  to  turn  water  into  rows  of  Fig.  94. 


356 


Irrigation   and    Drainage 


rods  long  and,  from  a  single  head  ditch,  sending  the 
water  the  whole  length.  They  were  nominally  using 
175  Colorado  inches  of  water,  distributing  it  in  alter- 
nate furrows. 

Before  going  home  at  night  they  divided  this  head 
between    40    rows    which     had     been    once     irrigated, 


Fig.  94.    Irrigating  potato  rows  40  rods  long  from  head  ditch  of  Fig.  92. 

gauging  the  flow  in  each,  so  that,  h}  their  judgment, 
the  lower  ends  of  the  furrows  would  be  nearly  reached 
on  their  return  in  the  morning.  After  watering  once 
begins,  it  is  kept  up  until  the  crop  is  matured,  going 
over  the  field  every  10  to  15  days. 

In  the  growing  of  potatoes  by  irrigation,  it  is  a 
matter  of  the  greatest  importance  that  the  ground 
shall  be  kept  well  moistened  continuously  after  the 
tubers  have  begun  to  form,  so  that  they  shall  be  kept 


Field   Irrigation   by   Furrows  357 

steadily  growing.  If  the  ground  is  allowed  to  become 
dry  enough  to  check  their  growth  and  another  irri- 
gation follows,  the  tubers  will  then  throw  out  new 
growths  and  become  irregular  in  form  and  unsalable. 

In  Colorado  the  potatoes  are  usually  planted  in 
rows  4  feet  apart.  This  distance  is  much  greater 
than  is  required  in  humid  climates,  and  it  would  seem 
that  were  the  same  amount  of  seed  planted  upon 
three-fourths  of  the  ground,  or  even  five-eighths, 
making  the  rows  36  inches  or  30  inches  apart  instead 
of  48  inches,  the  ground  could  be  more  thoroughly 
watered  and  larger  yields  per  acre  secured. 

It  is  certain  that  the  practice  of  only  watering 
alternate  rows,  which  is  common  where  water  is  scarce, 
does  not  permit  the  largest  yields  to  be  secured.  It 
has  been  shown  by  studies  in  the  humid  climate  of 
Wisconsin,  and  with  only  30  inches  between  the  rows, 
as  a  mean  of  two  years'  trials,  that  watering  between 
all  rows  gave  a  yield  of  317.3  bushels  per  acre  ; 
watering  between  alternate  rows  gave  277.1  bushels 
per  acre,  when  the  natural  rainfall  alone  gave  211.6 
bushels  per  acre.  That  is  to  say,  the  irrigation 
between  all  rows  increased  the  yield  over  the  natural 
rainfall  105.7  bushels  per  acre,  while  irrigating  between 
alternate  rows  only  increased  the  yield  65.5  bushels 
per  acre,  making  a  difference  between  the  two  methods 
of  irrigation  of  40.2  bushels  of  merchantable  tubers 
per  acre. 

In  these  experiments  the  field  was  divided  into  alter- 
nating groups,  which  were  watered  and  not  watered, 
so  that  there  were  two  rows  in  each  irrigated  plot 


358  Irrigation   and    Drainage 

watered  on  but  one  side,  and  it  was  the  yield  from 
these  rows  which  has  been  used  in  making  the  com- 
parison. 

It  was  also  found  that  the  first  row  not  irrigated 
on  either  side,  and  hence  standing  45  inches  from 
the  center  of  the  water  furrow,  had  its  yield  increased 
by  the  watering  only  7.9  bushels  per  acre.  This 
.makes  it  appear  that  were  the  potatoes  planted  in 
rows  90  inches  apart  and  the  water  applied  in  a  single 
furrow  between  each  two  rows,  the  benefit  derived 
from  the  water  would  be  much  less. 

It  is  very  clear,  therefore,  that  in  furrow  irriga- 
tion care  must  be  taken  that  the  water  is  not  led 
along  lines  too  distant  from  the  plants  which  are 
to  use  it. 

Where  the  water  is  to  be  allowed  to  run  some 
time  in  individual  rows,  and  where  considerable  quan- 
tities are  being  handled,  it  will  often  be  found  desir- 
able to  take  it  out  of  the  head  ditcli  into  short 
feeders  which  supply  a  certain  number  of  rows,  as 
represented  in  Fig.  95,  where  the  water  in  the  fore- 
ground is  in  the  head  ditch,  the  feeder  standing  next 
sending  water  into  8  rows  of  rape,  28  inches  apart 
from  center  to  center,  from  which  the  first  cutting 
has  just  been  removed. 

Sugar  beets,  maize,  and  all  field  crops  upon  which 
intertillage  is  practiced  would  be  irrigated  in  a  similar 
manner ;  but  in  such  close  planting  as  that  above 
on  sandy  loams  or  lighter  soils,  it  would  probably 
be  sufficient  to  lead  water  down  every  other  furrow, 
keeping  the  other  rows  under  frequent  flat  cultivation. 


Field  Irrigation   by   Furrows  359 

In  Italy,  where  so  much  work  is  done  by  hand,  it 
is  a  frequent  practice  to  throw  the  field  for  maize 
into  flat  ridges  or  beds  6  feet  wide  with  strong  irri- 
gation furrows  between,  planting  the  corn  in  an 
open  broadcast  manner  on  the  beds,  to  be  watered 


Fig.  95.    Dividing  water  between  eight  rows  of  recently  cut  rape. 

by  flooding  through  the  heavy  furrows.  .  'The  same 
practice  is  followed  to  some  extent  for  the  small 
grains  and  clover  also. 

WATER-MEADOWS 

Most  water-meadows  are  laid  out  with  the  view 
of  maintaining  a  continuous  flow  of  water  over  the 
whole  surface  for  considerable  periods  of  time,  with 


360  Irrigation    and   Drainage 

but  little  personal  attention.  Large  volumes  of  water 
are  usually  used,  and  in  Europe  especially  this  is 
applied  more  extensively  out  of  the  growing  season 
than  during  it,  or,  more  exactly  stated,  during  times 
when  the  crop  is  off  rather  than  when  on  the 
ground. 

Reference  has  already  been  made  to  the  water- 
meadows  near  Salisbury,  England,  where  Fig.  16 
shows  a  large  part  of  the  river  Avon  diverted  into 
a  canal  to  be  led  out  for  water-meadow  irrigation. 
In  Fig.  96  is  represented  a  diagram  of  one  of  these 
water-meadows  covering  about  15  acres.  The  solid 
lines  are  permanent  distributing  ditches  beginning  in 
the  head  distributary  and  ending  near  the  river  at 
the  foot  of  the  field.  They  are  placed  about  3  rods 
apart,  upon  the  crests  of  ridges  which  are  quite 
steep,  sloping  from  1  in  12  to  1  in  15  feet  toward 
the  dotted  lines,  which  are  permanent  drainage  fur- 
rows. It  is  on  this  field  that  the  photograph  shown 
in  Fig.  17  was  taken.  In  talking  with  a  "mead- 
man,"  whose  business  is  to  water  one  of  these  meadows, 
it  appears  that  water  has  been  run  over  them  year 
after  year  for  so  long  a  period  that  no  one  knows 
who  laid  them  out.  The  mead -man  in  question  was 
past  sixty  years  of  age,  and  both  his  father  and 
grandfather  had  been  mead -men  for  the  same  field. 
It  is  quite  probable,  therefore,  that  the  steep  slopes 
now  found  have  been  to  a  considerable  extent  a  mat- 
ter of  growth  due  to  deposit  of  sediments  in  the 
distributaries,  and  to  some  extent  to  erosion  along 
the  drainage  lines.  The  plan  of  this  system  of  irri- 


Wa  ter  -  Meadows 


361 


gallon  is  to  hold  the  distributaries  along  the  crests 
of  the  ridges  full  of  water  their  whole  length,  so 
that  it  shall  overflow  from  both  sides  and  run  down 


Fig.  96.    Plan  of  old  water-meadow,  Salisbury,  England. 

the  slopes  into  the  drainage  ditches  in  a  thin  and 
even  veil ;  and  in  order  that  this  shall  be  realized, 
the  distributaries  are  widest  at  the  upper  end,  grow-; 


362  Irrigation   and   Drainage 

ing  gradually  narrower  toward  the  foot,  while  the 
drainage  ways  increase  in  width  toward  the  foot.  In 
the  meadow  in  question,  the  measured  widths  and 
depths  of  the  distributaries  at  their  heads  were  42 
inches  by  24  inches  respectively,  in  all  except  Nos. 
10,  11,  12  and  13,  10  and  11  being  28  by  24,  12 
being  48  by  24  inches,  and  13  14  inches  wide  and 
12  inches  deep ;  but  the  capacity  of  the  drainage 
ditches  was  only  about  one -fourth  that  of  the  dis- 
tributaries. 

In  Italy  the  winter  meadows,  when  laid  out  in 
what  is  regarded  as  the  best  manner,  have  sloping 
faces  not  wider  than  25  to  30  feet,  and  with  the  crests 
12  inches  higher  than  the  hollows,  while  the  lengths 
are  quite  variable,  depending  upon  the  volume  of 
water  at  command,  but  usually  being  8  or  10  times 
the  width.  The  distributaries  have  a  width  of  12 
inches  and  a  depth  of  6  to  7  inches,  while  the  drain- 
age lines  have  dimensions  about  one -half  of  these. 

In  the  summer  water-meadows  of  Italy,  the  sur- 
face is  much  more  nearly  level  between  the  distribu- 
taries, and  often  there  is  no  intermediate  drainage 
furrow,  its  function  sometimes  being  fulfilled  by  a  line 
of  drainage  tile  beneath  the  surface. 

In  the  Campine  of  Belgium,  extensive  sandy  plains 
have  been  laid  out  in  water-meadows,  and  Fig.  97 
represents  a  small  section  of  this  system  near  Neer- 
pelt,  where  the  water  is  distributed  through  canals 
on  the  crests  of  ridges,  as  already  described,  and 
in  the  plan  the  heavy  lines  represent  the  distribu- 
taries, while  the  lighter  lines  represent  the  drainage 


364  Irrigation   and   Drainage 

system.  It  will  be  seen  that  the  land  is  laid  out 
so  as  to  use  the  surplus  drainage  water  over  again, 
by  collecting  it  into  a  foot  ditch  which  is  extended 
to  a  lower  level  in  the  field,  where  it  becomes  the 
head  ditch,  and  discharges  its  water  into  another  set 
of  distributaries,  as  represented  in  the  plan,  the  over- 


Fig.  98.    Model  of  field  laid  out  for  water-meadows,  with  slopes  exaggerated. 

flow  water  from  the  upper  section  being  used  upon 
the  third  or  lower  section.  The  area  shown  in  the 
plan  is  about  26  acres,  the  distance  between  the 
distributaries  about  two  rods,  and  the  crests  stand 
nearly  10  inches  above  the  troughs.  In  Fig.  98,  there 
is  represented  a  small  piece  of  ground  laid  out  upon 
this  plan  on  a  reduced  scale. 

It  will   be  seen   that   this  system  of  irrigation   not 
only  involves  a  large  amount  of   labor  to  fit  the  land, 


Irrigation    of   Cranberries  365 

but  it  throws  out  of  use  a  large  percentage  of  the 
area  irrigated,  while  at  the  same  time  greatly  inter- 
fering with  the  working  of  the  ground  and  harvesting 
of  the  crops.  Evidently  the  system  is  not  well  suited 
to  American  conditions  where  machinery  is  to  be  used. 
In  the  irrigated  mountain  meadows,  such  as  the 
one  represented  in  Fig.  14,  the  slopes  of  the  fields 
are  so  steep  that  the  water  is  usually  led  through 
irregular  furrows  whose  direction  is  determined  by 
the  natural  configuration  of  the  ground,  and  the 
practice  becomes  a  species  of  "wild  flooding"  where, 
on  account  of  the  great  fail,  the  water  is  distrib- 
uted without  much  labor  having  been  expended  in 
shaping  the  surface. 

IRRIGATION     OF     CRANBERRIES 

Cranberries  are  usually  grown  upon  very  level 
lands,  where  the  ground  water  is  naturally  at  or 
very  close  to  the  surface.  During  the  growing  sea- 
son, the  aim  is  to  hold  the  water  in  the  ground  to 
within  18  or  24  inches  of  the  surface,  but  on 
account  of  insect  ravages  and  frosts,  it  is  frequently 
imperative  that  the  lands  shall  be  flooded  quickly 
to  a  depth  of  6  to  10  inches,  and  the  water  drawn 
off  again  in  a  short  time.  To  prevent  winter -killing, 
it  is  also  desirable  to  flood  the  vines  and  hold  them 
under  water  until  the  danger  from  frost  is  past  in 
the  spring,  and  these'  requirements  make  it  necessary 
to  have  the  marshes  laid  out  as  represented  in  Fig. 
99,  where  blocks  of  land  are  surrounded  by  low 


366  Irrigation   and   Drainage 

dykes  and  wide  ditches,  and  at  the  same  time  divided 
into  narrow  lands  of  30  to  60  feet  by  parallel  nar- 
rower waterways,  which  are  at  once  distributaries  and 
drainage  ditches,  according  as  water  is  being  applied 
or  removed.  These  minor  distributaries  and  drainage 
lines  are  made  necessary  chiefly  by  the  necessity  of 
rapid  and  satisfactory  drainage  after  the  ground  has 


Fig.  99.    Plan  for  irrigation  of  cranberries. 

been  flooded  for  protection  against  insects  or  frost. 
The  side  ditches  may  be  3  to  5  feet  wide  and  2 
to  3  feet  deep,  according  to  the  size  of  the  area 
under  treatment,  while  the  minor  cross  -  ditches  should 
be  24  to  30  inches  wide  and  18  to  24  inches  deep. 

There   are   many   localities  where  the  land  is  suit- 
able  for   cranberry  culture,  but   where   running  water 


Irrigation   of   Cranberries 


367 


is  not  available  for  the  purpose  of  irrigation.  In 
some  of  these  localities  there  are  large  quantities 
of  water  in  the  ground  beneath  the  marshes,  which 
could  be  utilized  if  it  could  be  lifted  cheaply. 
Where  this  water  need  not  be  lifted  more  than  10 
to  20  feet,  and  where  there  is  an  abundance  of  it 
in  the  ground,  it  will  often  be  practicable  to  lay 


Fig.  100.    Plan  for  cranberry  irrigation  by  pumping. 

out  a  piece  of  ground  in  the  manner  represented  in 
Fig.  100,  with  a  reservoir  in  the  center  capable  of 
storing  water  enough  to  flood  the  balance  of  the 
ground  whenever  desired,  and  then  set  up  a  wind- 
mill of  sufficient  capacity  to  maintain  this  reservoir 
full  of  water,  letting  the  surplus  go  to  the  ditches 
if  needed  there,  to  hold  the  water  up  to  the  desired 
height  for  best  growth. 


368  Irrigation    and   Drainage 

The  object  of  placing  the  reservoir  in  the  center 
cf  the  area  to  be  controlled  is  to  utilize  the  seepage 
from  the  reservoir  to  hold  up  the  ground  water  to 
the  desired  level  more  readily.  A  12 -foot  steel  mill 
should  readily  handle  3  to  5  acres  if  the  water- 
supply  is  abundant,  the  ground  not  too  porous,  and 
the  lift  not  more  than  20  feet.  But  if  by  such  an 
arrangement  as  this  a  farmer  could  have  only  two 
acres  or  even  one  acre  of  cranberries  under  complete 
control  as  regards  frost  and  insects,  as  an  adjunct  to 
his  general  farming,  it  would  net  him  a  handsome 
profit  which  would  supplement  in  an  important  way 
his  yearly  income. 

It  would,  of  course,  be  necessary  to  be  able  to 
drain  the  area  quickly  after  flooding,  and  if  facilities 
are  not  the  best  for  this,  it  would  be  possible  to  so 
arrange  the  pump  that  the  water  could  be  thrown 
back  into  the  reservoir  again,  and  this  could  readily 
be  done  for  small  areas  where  an  engine  was  used 
instead  of  a  windmill  for  power. 

IRRIGATION     OF     RICE    FIELDS 

In  the  irrigation  of  rice  fields,  where  this  is  to 
be  done  under  the  best  conditions  and  where  the 
highest  quality  of  rice  is  to  be  produced,  it  is  a 
matter  of  prime  importance  that  the  fields  shall  be 
properly  laid  out,  and  that  an  abundant  supply  of 
suitable  water  shall  be  under  complete  control.  It 
has  been  pointed  out,  in  discussing  the  duty  of  water 
in  rice  culture,  that  available  statistics  make  the 


Rice   Irrigation  369 

average  amount  used  equal  to  a  flooding  of  the  field 
6  inches  in  depth  once  every  10  days,  and  since  so 
much  water  must  be  used  on  this  crop,  the  means 
for  handling  it  must  be  constructed  with  ample  pro- 
portions. 

In  South  Carolina,  at  the  mouths  of  the  Santee 
river,  where  the  natural  conditions  for  rice  culture 
exist  in  almost  ideal  perfection,  the  fields  have  been 
laid  off  into  flooding  basins,  varying  in  size  from 
a  few  acres  to  thirty  and  more.  Each  basin  is  sur- 
rounded by  a  dyke,  at  the  foot  of  which  is  a  main 
distributing  ditch  4  to  6  feet  wide  and  30  to  36 
inches  deep,  much  as  has  been  described  for  cran- 
berry irrigation,  but  on  a  larger  scale,  and  the 
resemblance  is  made  still  closer  by  the  division  of 
the  fields  into  narrow  lands  20  feet  in  width  by 
parallel  ditches,  36  inches  wide  and  36  inches  deep, 
which  are  at  once  the  ultimate  distributaries  and 
the  drainage  channels.  Trunks  or  sluices  are  pro- 
vided controlled  by  semi-automatic  tide  gates,  which 
may  be  raised  at  will,  on  the  sea  side,  to  admit 
the  water  to  these  ditches  and  flood  the  fields  to 
any  desired  depth,  and  then  closed  and  the  water 
retained ;  or  the  gate  on  the  field  side  may  be  raised 
and  the  water  withdrawn. 

After  the  fields  have  been  plowed  and  seeded  in 
the  spring,  they  are  flooded  to  a  depth  of  6  inches 
and  allowed  to  so  remain  until  the  seed  has  germi- 
nated and  the  first  three  roots  formed.  At  this 
stage  the  water  is  let  off  for  three  days  to  force 
rooting,  when  flooding  again  occurs  to  overtop  the 


370  Irrigation    and   Drainage 

plants  and  be  sure  to  submerge  the  highest  points 
in  the  field  and  start  the  rice  there.  This  done, 
the  water  is  drawn  to  a  gauge  and  changed  every 
seven  days  until  the  stage  for  dry  growth  has 
arrived,  after  21  days,  or  the  fifth  irrigation. 

The  water  is  now  held  off  during  30  days  and 
the  fields  are  given  two  dry  hoeings.  This  stirring  of 
the  surface  of  the  rice  fields  appears  to  have  two 
important  objects  to  secure:  (1)  to  destroy  weeds, 
and  (2)  to  so  aerate  the  soil  as  to  admit  air  to 
the  roots  and  to  the  niter  germs  for  the  develop- 
ment of  nitrates.  If  the  soil  is  not  stirred,  the 
plants  take  on  a  yellow  color,  which  quickly  changes 
to  a  dark  green  after  the  cultivation,  proving  this 
tillage  very  important.  During  this  time  the  dry- 
growth  roots  are  formed,  which  penetrate  the  soil 
sufficiently  to  enable  the  plants  to  stand  securely, 
while  at  the  same  time  they  absorb  the  nitrates, 
potash,  phosphoric  acid  and  other  ash  ingredients 
required  to  mature  the  grain. 

The  cultivation  is  made  more  urgent  on  these 
fields  because  of  the  fine  silt  borne  in  the  river 
water,  which  settles  and  overspreads  the  surface, 
forming  so  impervious  a  film  that  air  can  only  pass 
it  slowly,  and  if  not  broken  would  set  up  the  pro- 
cesses of  denitrification,  which  in  turn  must  check 
the  growth  of  the  crop  and  cause  it  to  turn  yellow. 

After  the  dry -growth  stage  has  been  passed  and 
the  head  is  ready  to  form,  the  7 -day  irrigations  are 
resumed  and  maintained  until  the  crop  has  been 
matured.  The  frequent  irrigations  are  necessitated 


Rice   Irrigation  371 

because  of  the  tendency  of  the  waters  to  become 
stagnant  and  poisonous  to  the  rice.  So  important  is 
the  complete  removal  of  the  stagnant  water  that  pro- 
vision is  made  at  the  farther  corner  of  each  field,  by 
means  of  a  trunk  in  the  dyke,  to  permit  the  water 
which  has  been  left  standing  in  the  ditches  after 
draining  to  be  forced  out  by  the  incoming  water  into 
another  ditch  leading  to  a  canal  or  creek,  and  careful 
watch  is  kept  until  the  yellow  river  water  has  finally 
reached  the  extreme  corner  and  forced  out  all  of  the 
standing  water  which  has  been  "  bagged "  in  the 
ditches. 

When  the  rice  crop  reaches  maturity  and  is  ready 
to  harvest,  a  few  of  the  topmost  kernels  are  more 
advanced  than  the  balance  of  the  head  and  certain  to 
shell  and  fall  upon  the  field.  These  tip  kernels,  too, 
are  liable  to  be  red,  and  if  allowed  to  germinate  the 
next  season  would  mature  heads  with  kernels  still 
more  highly  colored,  and  tend  in  a  short  time  to 
develop  the  "  red  rice "  which  so  seriously  lowers  the 
grade  and  market  price. 

To  avoid  the  development  of  red  rice  on  the 
marshes,  it  is  the  practice,  after  the  harvest  has  been 
removed,  to  again  flood  the  fields  and  germinate  at 
once  all  of  the  shelled  rice  which  has  fallen  upon  the 
ground,  so  that  the  winter  frosts  shall  kill  the  plants 
and  thus  remove  the  red  rice.  It  is  stated  that  if  the 
seed  is  placed  in  the  ground  where  it  cannot  ger- 
minate, it  may  retain  its  vitality  for  five  years,  and 
hence  where  the  practice  of  fall  flooding  cannot  be 
resorted  to  it  becomes  necessary  to  adopt  some  system 


372 


Irrigation    and   Drainage 


of  rotation  in  rice  culture  which  shall  furnish  oppor- 
tunity for  all  of  the  red  rice  to  have  been  germinated 
and  killed  before  another  crop  is  placed  upon  the 
ground,  and  it  is  the  great  ease  with  which  the  Caro- 
lina planters  are  able  to  control  this  difficulty,  and 
the  greater  cost  of  rotation  necessitated  by  other 


Fig.  101.    Plan  of  rice  irrigation,  as  practiced  in  South  Carolina. 

conditions,  which  gives  them  one  of  their  great 
advantages  over  other  rice -growers,  enabling  them  to 
command  the  highest  price  in  the  markets  of  the 
world. 

The  detailed  method  of  handling  water  on  a  Caro- 
lina rice  plantation  is  represented  in  Fig.  101,  where 
eight  of  the  many  fields  shown  in  Fig.  67  are 
represented  enlarged. 


Rice   Irrigation  373 

When  the  tide  falls,  the  gates  on  the  inner  ends  of 
the  trunks  automatically  close  and  prevent  the  escape 
of  the  water  during  any  desired  period,  while  the 
dropping  of  the  outer  gates  prevents  the  entrance  of 
any  more  water  until  they  are  again  raised.  To  drain 
the  fields  with  an  outgoing  tide,  it  is  only  necessary 
to  lift  the  inner  gates  and  the  work  goes  forward  to 
completion  without  further  attention,  so  that  the 
handling  of  the  water  both  ways  is  extremely  simple, 
effective,  and  remarkably  cheap. 

The  irrigation  of  rice  on  higher  lands  more  nearly 
resembles  the  irrigation  of  meadows  where  flooding  in 
checks  is  resorted  to,  except  that  here  the  checks  are 
filled  to  a  standard  gauge  with  water,  and  then  a  slow 
stream  is  kept  moving  into  and  out  of  them  as  long 
as  desired,  the  water  usually  entering  at  one  corner 
and  leaving  at  the  diagonally  opposite  corner.  The 
dividing  ridges  which  form  the  checks  have  a  height 
of  about  two  feet,  and  the  rice  fields  are  kept  under- 
water until  the  heads  are  formed,  when  the  water  is 
drawn  off  and  let  on  again  at  short  intervals  until  the 
kernels  are  well  formed,  when  the  water  is  removed 
and  the  fields  allowed  to  become  dry  and  the  grain 
mature,  preparatory  to  harvesting. 

ORCHARD     IRRIGATION 

In  orchard  irrigation,  several  methods  of  distribut- 
ing water  are  practiced,  but  there  is  none  followed 
so  generally  and  with  so  good  results  as  the  furrow 
method,  represented  in  Fig.  102,  where  the  water  is 


Orchard   Irrigation  375 

being  led  through  an  orange  orchard  in  an  ideal 
manner,  both  as  to  number  and  size  of  furrows  and 
volume  of  water  which  each  is  permitted  to  carry. 
The  aim  is  to  allow  small  streams  to  flow  slowly 
through  the  narrow  furrows  for  a  long  time,  until  the 
water  has  penetrated  by  percolation  deeply  beneath  the 
surface  and  at  the  same  time  has  spread  broadly  by 


Fig.  103.     Orchard  irrigation,  with  wooden  flume  in  foreground. 

capillarity  sidewise  under  the  surface  mulch.  In  Fig. 
103  is  shown  a  wooden  flume  box,  which  brings  the 
water  to  the  orchard,  delivering  it  to  the  several 
furrows  through  holes  in  the  side  which  are  %-inch 
to  1  inch  in  diameter,  and  which  are  prpvided  with 
wooden  buttons  or  metal  slides  for  regulating  the 
amount  of  water  admitted  to  each  furrow. 

The  appearance  of   the  furrows  after   the   capillary 
spread    has  been  considerable    is   represented  in   Fig. 


Fig.  104.    Capillary  spreading  of  water  through  soil  from  water  furrov 
in  peach  orchard,  Grand  Junction,  Colorado. 


Fig.  105.    Foot  ditch  for  one  orchard  and  head  ditch  for  loi 


Orchard   Irrigation 


377 


104.  When  the  stage  of  surface  wetting  shown  by 
the  dark  margins  of  the  furrows  has  been  reached, 
the  water  has  usually  percolated  to  a  depth  of  three 


Fig.  106.     Lower  orchard  taking  water  from  foot 
ditch  of  Fig.  105. 

or  more  feet,  and  has  at  the  same  time   spread  later- 
ally so  as  to  meet  beneath  the  furrows. 

Orchards  are  frequently  arranged  as  represented  in 


378 


Irrigation    and    Drainage 


Fig.  107.    Head  ditch  or  cement  flume  for  orange  orchard, 
Badlands,  California. 

Figs.  105  and  106,  so  that  the  surplus  water  from  the 
furrows  in  the  upper  one  is  collected  in  a  foot  ditch 
shown  in  the  center  of  Fig.  105,  and  redistributed  in 
a  second  set  of  furrows  crossing  a  lower  level,  shown 
in  Fig.  106.  The  water  may  be  controlled  by  a  simple 
gate  in  a  sluice -box,  shown  at  1,1  in  Figs.  105  and 


Orchard   Irrigation  379 

106,  which  permits  as  much  water  to  pass  from  the 
foot  ditch  into  the  lower  furrows  as  is  desired.  This 
method  of  irrigation  is  always  less  economical  of 
water  than  where  the  water  admitted  to  each  furrow 


Fig.  108.     Large  young  orchard  on  gravelly  flood  plain  of 
Santa  Ana  river,  with  cement  flume. 

is   so   nicely   adjusted  that  there    is  no    waste  into  a 
foot  ditch.     So,  too,  is  there  less  waste  land. 

Still  another  method  of  utilizing  the  water  which 
may  waste  at  the  foot  of  the  orchard  is  to  have  there 
a  strip  of  alfalfa,  clover  or  grass  to  take  this  surplus 
with  little  or  no  attention  or  waste. 


380  Irrigation   and   Drainage 

But  where  cement  or  wooden  distributing  flumes, 
such  as  are  shown  in  Figs.  107  and  108,  are  used, 
it  is  usually  quite  easy  to  so  completely  control  the 
discharge  that  no  waste  need  occur,  and  in  cases 
where  water  is  scanty  and  expensive  this  method  is 
adopted  to  great  advantage. 


Fig.  109.     Model  of  orchard  irrigation  by  ring  furrows. 

When  the  trees  of  an  orchard  are  young,  it  is 
quite  unnecessary  to  irrigate  the  whole  ground,  and 
a  common  practice  is  to  make  a  furrow  around  each 
tree,  as  represented  in  Fig.  109,  allowing  the  water 
to  flow  along  the  single  distributing  furrow,  sending 
it  into  the  side  rings  for  12  or  24  hours  until  a  cone 
of  saturated  soil  is  secured  below  each  tree.  As  the 


Cultivation    After   Irrigation  381 

trees  become  older,  the  encircling  furrows  may  be 
made  larger,  until  finally  it  is  better  to  lead  the  water 
along  two  single  furrows  on  each  side  of  the  row, 
as  shown  in  Figs.  104  and  106.  With  increasing 
spread  of  root,  the  number  of  furrows  would  be 
increased  until  ax  watering  of  the  whole  ground  has 
become  needful. 

CULTIVATION    AFTER     IRRIGATION 

A  cardinal  principle  in  orchard  irrigation  should 
ever  be  thorough,  deep  saturation,  followed,  as  soon 
as  the  soil  will  permit,  with  thorough  cultivation,  fre- 
quently repeated.  In  Fig.  110  is  represented  an  excel- 
lent mulch-producing  tool  for  orchard  work.  It  is 
drawn  by  three  horses  ;  can  be  set  to  run  at  any 
depth  ;  makes  a  clean  cut  of  the  whole  soil  without 
bringing  the  moist  portion  to  the  surface,  and  is 
provided  with  a  steering  wheel,  which  permits  the 
driver  to  easily  throw  one  end  of  the  long  cutting 
blade  quickly  and  accurately  to  one  side  and  bring  it 
close  to  the  trunk  of  a  tree  without  driving  the  team 
near  enough  to  endanger  either  the  trunk  or  limbs. 
As  the  blade  of  the  tool  is  8  feet  long,  the  orchard 
may  be  covered  quickly  with  it.  Smaller  sizes,  with 
5 -foot  blades,  are  also  on  the  market  in  California. 

Another  form  of  orchard  cultivator  to  which  fur- 
row plows  may  be  attached  is  represented  in  Fig.  111. 
Ordinary  forms  of  cultivators  must  necessarily  tend 
more  to  invert  the  soil  and  bring  the  wet  portions  to 
the  air,  and  thus  be  less  economical  of  moisture.  They 


Fig.  110.    Three-horse  orchard  cultivator  used  at  San  Jose,  California. 


Fig.  111.    Combined  orchard  cultivator  and  furrowing  tool. 


Cultivation   After   Irrigation  383 

have,  however,  advantages  over  the  other  form  for 
going  over  the  ground  the  first  time  after  irrigation, 
when  it  is  important  to  break  the  moist  soil  into  a 
crumbled  condition. 

Systems  of  flooding  are  also  adopted  in  orchard 
irrigation,  sometimes  flooding  the  whole  ground  or 
small  checks  surrounding  the  trees,  when  these  are 
young  and  the  water  scanty,  but  this  method  is  far 
more  wasteful  of  water  and  much  more  injurious  to 
the  texture  of  the  soil,  unless  it  is  sandy.  When 
following  it,  care  must  be  taken  to  prevent  water  from 
coming  against  the  trunks  of  the  trees  and  stand- 
ing there. 

In  humid  climates,  on  lands  where  the  soil  will 
not  wash  badly,  the  methods  of  orchard  cultivation 
practiced  in  the  west  would  give  far  better  results 
than  leaving  them  so  persistently  in  grass,  as  is  the 
more  common  practice.  The  moisture  of  the  soil 
should  be  saved  for  the  trees  as  a  rule,  rather  than 
used  for  any  other  crop  after  the  trees  become  large. 

SMALL -FRUIT     IRRIGATION 

In  the  irrigation  of  strawberries,  raspberries,  black- 
berries, and  similar  fruits,  the  furrow  method  will 
almost  always  be  practiced,  leading  a  slender  stream 
along  each  side  of  the  row  and  quite  close  to  it. 

Blackberry  and  raspberry  roots  penetrate  to  a  suf- 
ficient depth  to  permit  a  thorough  saturation  of  the 
soil  and  good  cultivation  before  the  berries  are  ready 
to  pick,  so  that  no  irrigation  will  be  required  during 


384  Irrigation   and    Drainage 

the  picking.  Strawberries,  however,  are  so  shallow- 
rooted  that  water  enough  cannot  be  placed  within 
reach  of  the  plants  to  make  irrigation  during  the 
picking  season  unnecessary.  It  is,  therefore,  a  com- 
mon practice  to  lay  out  strawberry  fields  in  such  a 
way  that  the  water  may  be  led  only  between  alternate 
matted  rows  in  deep  broad  furrows,  holding  the  water 
well  up  the  sides  so  that  it  may  better  spread  laterally 
under  the  plants.  This  practice,  although  not  as 
economical  of  water  as  irrigating  between  every  row, 
has  the  advantage  of  not  seriously  interfering  with 
picking,  there  being  always  sufficiently  firm  ground 
upon  which  to  walk. 

GARDEN    IRRIGATION 

Garden  vegetables  are  oftenest  raised  in  beds  and 
patches  of  such  small  dimensions,  and  on  soils  so 
light  and  open,  that  the  irrigation  of  them  is  accom- 
plished most  readily  by  methods  closely  allied  to  those 
of  flooding.  A  relatively  large  volume  of  water  is 
quickly  brought  to  the  point  needed  and  applied  all 
at  once,  and  without  waiting  for  either  percolation  or 
capillary  spreading  to  take  place. 

A  method  represented  in  Fig.  112  consists  in  lay- 
ing the  ground  off  into  beds,  and  getting  the  seed 
planted,  when  the  surface  is  overspread  with  a  thin 
dressing  of  rather  coarse  litter  or  horse  manure. 

Water  is  turned  into  the  head  ditch,  which  is 
choked  with  a  little  soil  or  an  irrigator's  broad 
hoe  set  so  as  to  turn  the  stream  between  the 


v    Garden   Irrigation 


385 


beds,  when  the  irrigator  dams  the  current  at  his  feet 

with   a   gunny   sack   and   with   a   long  -handled    basin 

dextrously  bales  the  water  out  as  rapidly  as  it  reaches 

him,  dashing  it  over 

the    littered     surface 

until,  in  his  judgment, 

water  enough  has  been 

applied.     The  dam  is 

then    moved    and     a 

second  area  irrigated, 

the    operation    being 


Fig  112    Diagram  of  garden  beds. 


repeated     until      the 

ends  of  the  beds  have 

been    reached,  when   the    head    ditch    is    opened    and 

closed  in  another  place,  turning  the  water  in  between 

other  beds. 

When  the  water  has  had  time  to  penetrate  the 
soil,  when  the  surface  is  beyond  danger  of  crusting, 
and  the  delicate  plants  have  begun  to  emerge  from 
the  ground,  the  litter  may  be  raked  off.  In  this 
manner  a  man  was  observed  to  irrigate  an  area  33 
feet  by  150  feet  in  one  hour,  using  the  water  which 
could  flow  through  a  short  3-inch  pipe,  filling  it  half 
full,  and  Fig.  112  is  a  diagram  of  the  beds,  15  feet 
wide  between  the  waterways. 

Another  type  of  irrigation  is  shown  in  Fig.  113, 
where  the  garden  is  ridged  and  furrowed  every  18 
inches.  Celery  is  planted  on  one  side  of  each  ridge 
and  lettuce  on  the  other.  When  irrigation  is  required 
the  furrows,  6  inches  deep,  are  flooded  one  at  a  time 
from  a  stream  led  along  their  head,  and  these,  when 


386 


Irrigation  and  Drainage 


Fig.  113.    Furrow  flooding  in  garden. 

quickly  filled,  are  supposed  to  hold  sufficient  water 
for  one  irrigation,  enough  to  cover  the  whole  ground 
2.5  to  3  inches.  In  Fig.  114  is  represented  a  cross 
section  of  the  rows. 

In  still  other  cases  shallow  basins  are  formed 
about  each  row  of  plants,  as  represented  in  Fig.  115, 
where  cabbages  have  been  set.  It  will  be  noted  that 
the  basins  are  not  only  narrow  but  short,  so  that 

each    may   be    quickly  filled, 

one    after    another,    from    a 

i  j      i  11 

stream    led    along    an    alley 

Fig.  114.     Diagram  of  section  of  rows    between      two     Sets.         As     the 
and  furrows  in  Fig.  113.  ,  ,  , 

plants     become     larger     the 

ridges  are  gradually  cut  down  to  hill  the  plants,  and 
thus  form  water  furrows  in  their  stead.  This  is  one 


Garden   Irrigation 


387 


method,  as  practiced  by  the  Italian  gardeners,  both 
in  their  native  country  and  on  the  sandy  lands  at 
Ocean  View,  south  of  San  Francisco. 

In  Fig.  116  is  shown  another  cabbage  field  recently 
transplanted  by  the  Chinese  gardeners  at  San  Ber- 
nardino, Cal.  In  this  case  the  field  is  quickly  and 
roughly -ridged  and  then  the  large  plants  hastily  set 
low  down  in  one  side  of  the  ridge.  After  irrigation, 
and  when  the  water  has  settled  away  so  as  to  permit 
working,  a  little  soil  from  the  ridge  is  pulled  about 
the  plants,  as  seen  in  the  cut.  In  time  the  whole 
ridge  has  been  pulled  over,  leaving  the  plants  stand 
ing  in  the  center  of  the  crest. 

The    French    about    Paris    throw    their    fields   into 
broad   double  ridges,  wide    enough   to  carry  two  rows 


Fig.  115.     Basin  flooding  of  cabbage  in  garden  of  sandy  soil. 


388  Irrigation   and   Drainage 

of  vegetables  24  inches  apart,  and  these  are  sepa- 
rated by  furrows  a  foot  wide  and  6  inches  deep, 
through  which  water  is  led  for  irrigation,  and  Fig. 
117  is  a  plan  of  a  section  of  the  upper  end  of  a  cab- 
bage field  as  laid  out  on  the  valley  sands  of  the  river 
Seine,  just  outside  the  city  walls. 


Fig.  116.    Chinese  method  of  irrigating  cabbage, 
San  Bernardino,  California. 

Melons  and  cucumbers  are  planted  upon  still 
broader,  ;<be<|s,  6  to  8  feet  wide,  separated  by  water 
furrows,  as*  represented  in  Fig.  118,  the  hills  being 
planted  near  each  margin  of  the  bed  and  the  vines 
trained  away  from  the  furrows. 

At  Rocky  Ford,  Colorado,  where  melons  are  raised 


Garden   Irrigation 

on  a  large  scale,  fields  are  furrowed  every  6  feet 
with  a  double  shovel  plow.  The  seeds  are  'planted 
in  the  edge  of  the  ridge  away  from  the  furrows,  and 
the  soil  watered  through  the  furrow  only,  by  lateral 
capillary  flow,  great  care  being  taken  to  avoid  flood- 
ing the  surface.  Cultivation  follows  each  irrigation 
after  the  plants  are  up  until  the  vines  become  too 
large,  but  watering  must  be  kept  up  about  once  in 
ten  days  until  the  crop  is  mature. 


Fig.  117.     Diagram  ot  cabbage  irrigation  at  Gennevilliers,  near  Paris. 


Another  system  of  irrigating  gardens  is  repre- 
sented in  Fig.  119,  where  the  rows  are  hilled,  leav- 
ing shallow  furrows  between  them,  but  arranged  so 
that  a  stream  of  water  can  be  led  across  the  ends 
and  turned  into  them  one  by  one.  The  water  is  led 
to  the  lower  rows  down  the  middle  furrow,  and  with 
a  broad  irrigating  hoe,  having  a  blade  12  inches 


390 


Irrigation   and  Drainage 


|Fig.  118.     Irrigation  of  melons  and  cucumbers  by  Chinese  at  San  Bernardino. 

long  and  10  inches  deep,  the  soil  at  1  is  quickly 
turned  over  to  2,  to  form  a  dam  in  the  stream, 
thus  allowing  the  water  to  flow  between  the  two 
lower  rows  until  that  furrow  has  been  filled  to  a 
sufficient  height.  The  soil  from  3  is  then  turned 
over  to  1,  thus  closing  1  and  allowing  the  water  to 
enter  3.  When  3  is  full  the  soil  from  4  is  brought 
back  to  5,  which  turns  the  stream  in  there.  When 
4  has  received  enough,  the  water  is  turned  into  6 
by  moving  the  soil  from  there  to  4.  In  this  manner 
the  irrigator  advances  from  row  to  row  until  both 
sides  of  the  whole  bed  have  been  watered. 

In    other    cases,    small    or    large    areas  of   garden 
plants  are  enclosed  in  small,  shallow  basins  by  throw- 


Garden   Irrigation 


391 


ing  up  minute  dyke -like  ridges  not  more  than  6 
inches  wide  and  4  high.  These  basins  may  be 
arranged  in  a  single  or  double  chain,  and  the  water 
led  down  one  side  or  between  them.  In  this  case, 
again,  the  watering  would  usually  begin  at  the  lower 
end,  and  with  the  hoe  a  section  of  the  border  of  a 
basin  would  be  drawn  out  to  act  as  a  dam  across 
the  stream,  as  shown  in  Fig.  120.  The  soil  from  1 


Fig.  119.    Plan  of  fiirrow  garden  flooding  by  successive  rows. 

and  2  would  be  drawn  around  to  3,  thus  turning 
the  water  into  both  beds.  When  these  were  watered, 
the  soil  from  4  and  5  would  be  drawn  around  to 
6,  and  the  next  two  beds  irrigated.  In  this  manner 
the  gardener  advances  rapidly  from  bed  to  bed  with 
but  little  trouble  and  labor. 


THE    IRRIGATION    OF    LAWNS    AND    PARKS 

It  should  ever  be  kept  in  mind,  where  shrubbery, 
trees    and    grass   are    grown    together,  as   is   so   com- 


392 


Irrigation   and   Drainage 


monly  the  practice  in  humid  climates,  that  two  crops 
are  being  grown  at  the  same  time  upon  the  land,  and 
that  under  these  conditions  more  water  is  demanded. 
The  roots  of  shrubs  and  trees  are  more  deeply  placed 
in  the  subsoil  than  are  most  of  those  which  feed  the 
lawn  grass,  and  hence  all  rains  too  light  to  over- 
saturate  the  surface  6  inches  are  practically  secured 
by  the  grass,  and  since  to  maintain  a  good  lawn 


Fig.  120.    Plan  of  basin  flooding  in  garden  irrigation. 

requires  more  water  than  ordinarily  falls  as  rain, 
even  in  quite  humid  climates,  it  follows  that  in  all 
public  parks,  cemeteries  and  ornamental  grounds  about 
homes,  there  should  be  provided  an  abundant  supply 
of  water  for  thorough  irrigation. 

In  watering  lawns  and  parks,  so  much  water  is 
demanded  that  it  ought  usually  to  be  applied  by 
some  flooding  system  rather  than  by  spraying,  as 


Lawn   and   Park   Irrigation  393 

is  so  commonly  the  practice.  The  truth  of  this 
statement  will  be  readily  appreciated  when  it  is 
observed  that  in  order  to  saturate  good  lawns  suffi- 
ciently to  force  any  water  down  where  it  will  become 
available  to  the  roots  of  trees  and  shrubbery,  the 
ground  must  receive  not  less  than  2  to  3  inches  in 
depth  of  water.  But  to  apply  this  amount  with 
spraying  nozzles  is  impracticable. 

If  public  parks  and  cemeteries  were  more  gen- 
erally laid  out  with  a  view  to  thorough  irrigation 
as  a  part  of  their  proper  care  all  through  the  cen- 
tral and  eastern  United  States,  not  only  would  the 
growth  of  shrubbery  and  trees  be  far  more  luxuriant 
and  satisfactory,  but  dry  seasons  would  not  destroy 
the  many  beautiful  trees  which  so  often  succumb  to 
drought  just  in  their  prime. 

Wherever  a  good  well  can  be  had  with  abundance 
of  water  and  a  lift  not  to  exceed  50  feet,  a  lawn  of 
half  an  acre,  with  its  shrubbery,  together  with  a 
vegetable  garden  or  fruit  orchard  of  several  acres, 
may  easily  be  irrigated  with  a  plant  not  costing 
more  than  $300  to  $500.  Such  a  plant  is  repre- 
sented in  Figs.  121  and  122.  This,  including  well- 
house,  2%  horse -power  gasoline  engine  and  double- 
acting  pump,  having  a  capacity  of  80  gallons  per 
minute,  with  over  1,000  feet  of  2 -inch  distributing 
pipe  and  hose,  cost,  when  put  in  place  ready  for 
work,  $440. 

In  the  portion  of  this  plant  shown  in  Fig.  122, 
part  of  the  2 -inch  iron  distributing  pipe  for  the 
lawn  and  garden,  as  represented  at  B,  C  and  D, 


394 


Irrigation   and   Drainage 


are  tapped  every  3  feet  for  short  half -inch  nipples 
with  caps.  With  this  arrangement  it  is  easy  to 
take  out  water  at  any  desired  place,  pressure  being 


Fig.  121.     Small  gasoline  pumping  plant  for  garden  and  lawn  irrigation. 

maintained  in  the  whole  system  of  pipes  when  the 
pump  is  at  work.  The  pipes  for  watering  the  lawn 
are  sunk  just  flush  with  the  sod,  and  the  nipples 
rise  obliquely  upward  so  short  a  distance  as  not  to 
interfere  with  the  lawn  mower.  The  arrows  show 
both  the  slope  of  the  lawn  and  the  way  the  water 
is  distributed.  By  opening  only  7  to  10  nipples  at 
a  time,  a  large  volume  of  water  is  secured,  which 
spreads  readily  over  the  surface.  In  the  garden  irri- 
gation, 15  or  20  rows  may  be  watered  at  once,  and  if 


Lawn   and   Park   Irrigation 


395 


a  particular  stream  is  a  little  too  strong,  this  may 
be  regulated  by  thrusting  a  bit  of  stick  into  the 
nipple.  For  watering  beds  about  the  house,  four  of 


Fig.  122.    Plan  of  lawn  and  garden  irrigation. 

the  nipples  are  made  for  attaching  a  garden  hose, 
which  may  also  be  used  to  wash  windows  or  a  car- 
riage. Altogether,  this  arrangement  is  very  simple 
and  satisfactory  for  a  suburban  or  country  home, 


396  Irrigation   and   Drainage 

and    would    answer    admirably    for    a    small    market- 
garden,  where  vegetables  and  fruits  are  raised. 


SUB -IRRIGATION 

This  method  of  applying  water  consists  in  plac- 
ing lines  of  tile  or  perforated  pipe  varying  dis- 
tances below  the  surface  of  the  soil,  and  distributing 
water  through  these  instead  of  in  furrows  or  by 
methods  of  flooding.  This  system  of  irrigation 
quickly  suggests  itself  to  most  thoughtful  men  when 
they  first  begin  to  handle  water  for  irrigation,  on 
account  of  the  many  difficulties  and  inconveniences 
which  are  associated  with  surface  wateric  or ;  but  there 
are  several  very  fundamental  objections  to  it  which 
have  usually  led  to  its  abandonment  sooner  or  later 
in  nearly  every  place  where  tried. 

Were  it  not  for  the  objections  just  referred  to, 
sub -irrigation  would  constitute  an  ideal  method  of 
applying  water,  and  would  be  universally  practiced. 
Could  it  be  used,  much  of  the  expense  of  fitting 
the  surface  would  be  avoided ;  the  fields  would  be 
almost  wholly  unobstructed  ;  all  of  the  ultimate  dis- 
tributaries would  become  permanent  improvements ; 
the  surface  of  the  soil  could  not  become  puddled ; 
mulches  developed  would  not  be  periodically  destroyed, 
and  the  duty  of  water  would  be  vastly  increased. 
Indeed,  so  many  things  appear  to  be  in  favor  of  the 
method  that  it  is  only  with  great  reluctance  that  it  is 
abandoned. 

The   most  insuperable  difficulty  with  sub -irrigation 


Sub -Irrigation  397 

is  that  of  applying  sufficient  water  to  thoroughly  wet 
the  surface,  and  yet  those  who  have  not  tried  the 
plan  feel  confident  that  there  will  be  a  great  saving 
in  this  direction  ;  but  the  rate  of  capillary  movement 
of  water  in  soil  is  relatively  so  slow,  and  percolation 
so  rapid  in  most  cases,  that  it  becomes  nearly  imper- 
ative that  water  shall  be  placed  upon  the  surface, 
where  it  is  most  needed  and  is  of  greatest  service. 

It  has  been  shown  under  furrow  irrigation,  where 
the  water  is  applied  at  the  surface,  that  the  streams 
must  usually  be  led  as  close  as  every  four  feet,  to  wet 
the  whole  ground,  and  from  this  it  follows  that  lines 
of  tile  laid  even  closer  than  this  would  be  required 
in  sub -irrigation.  In  Fig.  123  is  shown  the  wetting 
of  the  surface  which  occurred  by  distributing  the 
water  through  3 -inch  tile  placed  18  inches  below  the 
surface,  in  which  hydrostatic  pressure  was  maintained 
sufficient  to  cause  the  water  to  rise  one  or  two  inches 
above  the  top  of  the  ground.  ,  In  this  experiment 
the  tile  were  arranged  as  represented  at  D,  Fig. 
124,  10  feet  apart,  and  it  will  be  seen  that  only 
about  3  feet  in  width  above  each  line  of  tile  has  been 
wet,  and  yet  water  enough  has  been  applied  to  cover 
the  area  more  than  6  inches  deep.  Even  at  C,  Fig. 
124,  where  the  tile  are  only  5  feet  apart,  it  was 
necessary  to  apply  19.68  inches  of  water  in  depth  to 
completely  we,t  the  surface,  but  in  this  case  the  sub- 
soil was  more  open  than  it  was  at  D.  It  is  plain, 
therefore,  that  in  order  to  thoroughly  wet  the  sur- 
face of  the  ground  by  sub -irrigation,  much  more 
water  will  be  required  than  by  furrow  irrigation, 


398 


Irrigation   and   Drainage 


unless   the   tile   are    as   close  as  4  feet  apart  and  very 
near  the  surface. 

The  second  great  obstacle  in  applying  sub-irriga- 
tion is  the  expense  required  to  purchase  and  place  the 
necessary  lines  of  tile.  In  watering  strawberries, 


Fig.  123.     Difficulty  of  wetting  surface  soil  by  sub-irrigation. 

blackberries,  raspberries,  and  other  small  fruits,  one 
line  of  tile  would  be  required  under  each  row.  For 
orchard  irrigation,  two  lines  of  tile  would  be  needed, 
one  on  each  side  of  the  row  when  the  trees  are  small, 
and  the  number  would  have  to  be  increased  as  the 
trees  reached  maturity,  until  there  was  at  least  one 
every  5  feet.  For  general  field  crops,  the  number  of 


Sub -Irrigation 


399 


tile  could  scarcely  be  less  than  one  line  every  5  feet, 
and  it  would  be  necessary  to  place  them  at  least  far 
enough  below  the  surface  not  to  be  disturbed  in 
working  the  soil  in  crop  rotation. 


Fig.  124.    Flan  of  fields  for  sub-irrigation  experiments. 

At  one  cent  per  foot  for  3 -inch  drain  tile,  the  cost 
for  pipe  alone  would  be  $87.12  per  acre  where  the 
lines  are  laid  5  feet  apart.  In  addition  to  this  ex- 
pense, there  would  be  the  cost  of  transportation, 
bj-eakage,  and  laying  of  tile  connecting  with  the  head 


400  Irrigation    and    Drainage 

ditch,  and  maintenance,  which,  in  the  aggregate, 
could  not  be  less  than  $12.88  per  acre  when  done  on 
a  large  scale  and  under  the  most  favorable  conditions, 
or  a  total  cost  of  $100  per  acre,  at  the  very  best 
figure  which  could  be  hoped  for. 

Only  in  those  cases  where  tile  could  be  placed 
barely  below  the  surface  could  there  be  as  high  a 
duty  of  water  as  with  furrow  irrigation,  and  hence, 
where  water  is  high  and  labor  cheap,  the  cost  of  water 
would  decide  against  sub -irrigation. 

Where  a  field  has  been  underdrained,  as  repre- 
sented in  Fig.  124,  in  the  lower  lefthand  corner,  it  is 
easy  to  introduce  the  irrigation  water  at  the  upper 
end  of  the  main,  as  shown  at  F,  and  allow  it  to  set 
back  through  the  laterals.  By  forcing  the  water  in 
the  main  to  rise  to  the  surface  of  the  ground  at  G, 
H  and  A  before  passing  on  to  lower  levels,  the 
water  in  all  the  tile  would  be  placed  under  pressure 
which  would  force  it  to  the  top  of  the  ground  with- 
out waiting  for  capillarity  to  bring  it  there.  In 
this  manner  if  the  field  were  underlaid  by  sand  at  the 
level  of  the  tile,  the  whole  area  may  be  quickly 
watered,  provided  the  main  has  capacity  sufficient  to 
deliver  the  water  to  all  the  laterals  as  rapidly  as 
percolation  can  take  place  from  them.  With  the 
outlet  of  the  tile  at  E  closed  and  water  admitted  to 
the  main  at  both  F  and  A,  the  7,022  feet  of  tile  took 
water  at  the  rate  of  48  cubic  feet  per  minute  under 
the  5  acres,  or  at  the  rate  of  5  gallons  per  100  run- 
ning feet  of  tile  where  these  were  placed  in  sand  33 
feet  apart.  During  the  irrigation,  water  was  brought 


Sub  -  Irrigation  401 

to  the  surface  along  most  of  the  lines  of  tile,  as 
represented  by  the  dotted  area  below  A.  To  do  this 
work,  5.8  inches  of  water  on  the  level  were  required, 
but  it  is  quite  certain  that  half  this  amount  applied 
at  the  surface  in  the  proper  manner  would  have  ren- 
dered as  much  service.  The  time  required  to  apply 
the  water  at  the  surface  would  have  been  about  the 
same,  but  an  extra  man  would  have  been  needed  to 
distribute  it,  and  the  furrows  would  have  to  be  made, 
so  that  there  is  this  labor  to  be  offset  by  the  cost 
of  the  extra  amount  of  water  required  for  the  sub- 
irrigation. 

But  it  must  be  kept  in  mind  that  had  the  field 
not  been  underlaid  by  sand  and  the  ground  water 
surface  near  the  level  of  the  tile,  and  had  the  pressure 
not  been  held  up  so  as  to  force  the  water  to  rise  to 
the  surface,  these  results  could  not  have  been  attained 
with  tile  placed  as  far  apart  as  33  feet.  The  applica- 
tion of  sub -irrigation  to  tile -drained  areas  cannot, 
therefore,  be  regarded  as  the  best  method  of  watering 
in  any  but  special  cases. 

It  is  quite  probable  that  were  this  system  of 
irrigation  to  be  applied  to  water-meadows  to  avoid 
surface  ditches,  or  even  to  orchards  and  small  fruits, 
there  might  be  experienced  difficulties  arising  from 
the  tile  becoming  clogged,  either  from  sediments 
moved  by  the  water  or  by  the  growth  of  roots  into 
the  lines  of  tile.  • 

When  the  difficulties  which  have  been  pointed  out 
as  standing  in  the  way  of  sub -irrigation  are  con- 
sidered, and  when  it  is  recalled  that  nitrification  in 


402  Irrigation   and   Drainage 

most  soils  can  take  place  only  near  the  surface,  when 
roots  are  better  aerated  there,  and  when  here  alone 
can  germination  occur,  it  seems  plain  that  there  can 
be  little  reason  to  hope  much  from  this  method  of 
applying  water. 


CHAPTER  XI 

SEWAGE   IRRIGATION 

THE  methods  of  distributing  water  in  sewage  irri- 
gation are  essentially  the  same  as  those  already  de- 
scribed. The  topography  of  the  field  to  be  watered 
and  the  character  of  the  soil  or  of  the  crop,  will 
determine  which  method  shall  be  employed.  It  re- 
mains here  to  state,  from  the  agricultural  side  of  the 
subject,  under  what, conditions  sewage  irrigation  may 
be  practiced  to  advantage  and  what  crops  are  best 
suited  to  utilize  the  water. 

OBJECTS    SOUGHT    IN    SEWAGE    IRRIGATION 

There  are  two  main  objects  sought  in  the  use  of  sewage 
in  irrigation.  The  first  and  primary  one  is  to  oxidize  and 
render  innocuous  the  organic  matter  which  it  contains.  The 
secondary  object  is  to  utilize  this  organic  matter,  together  with 
the  water  and  other  fertilizers  which  it  may  contain,  in  the 
production  of  crops.  Reference  has  already  been  made  to  this 
point  in  connection  with  the  Craigentinny  Meadows,  where  a 
poor  soil  has  been  made  to  yield  a  gross  income  of  $75  to 
more  than  $100  per  acre  per  annum  for  nearly  a  century. 

The  oxidation  and  denitrification  of  the  organic  matter  borne 
in  the  sewage  water  must  be  accomplished  largely,  if  not  wholly, 
through  the  agency  of  fermenting  germs,  and  this  being  true, 
it  is  imperative  that  the  methods  of  treatment  shall  be  favor- 
able to  the  activity  of  these  forms  of  life. 

(403) 


404  Irrigation    and    Drainage 

CLIMATIC    CONDITIONS    FAVORABLE    TO    SEWAGE 
IRRIGATION 

Since  the  fermentive  processes  which  convert  organic  matter 
either  into  nitric  acid,  which  is  the  nitrogen  supply  for  most 
cultivated  crops,  or  into  free  nitrogen  gas  can  take  place  rap- 
idly only  under  temperatures  above  50°  F.,  it  follows  that  sewage 
irrigation  is  best  suited  to  warm  climates,  where  crops  may 
be  grown  the  year  round,  and  where  the  fermentive  processes 
will  be  least  checked  by  frosts.  In  tropical  and  semi-tropical 
climates,  therefore,  sewage  disposal  by  surface  irrigation  may 
best  be  practiced  when  other  needful  conditions  are  also  favor- 
able. 

In  cold  climates,  like  those  of  the  northern  United  States 
and  Canada,  where  the  ground  is  frozen  during  five  months  or 
more  of  each  year,  it  is  plain  that  only  about  one-half  of  the 
sewage  water  can  be  used  in  crop  production,  and  that  during 
only  about  one -half  of  the  year  can  there  be  much  oxidation 
and  denitrification  of  organic  matter.  Under  these  conditions, 
therefore,  if  water  is  applied  to  land  one -half  of  it  must  be 
filtered  by  the  soil  without  the  concurrent  purification  which 
results  from  fermentation,  and  this  being  true,  there  can  be 
only  so  much  of  purification  as  naturally  results  from  the 
physical  filtration  and  such  chemical  fixation  as  the  soil  may  be 
capable  of  accomplishing. 

It  is  true  that  the  purification  of  sewage  resulting  from 
filtration  through  soil  is  very  considerable,  so  that  if  isolated 
lands  of  sufficient  area  are  selected  for  this  purpose,  the  organic 
Impurities  reaching  the  ground  water  will  be  greatly  reduced. 
It  is  also  true  that  in  cold  climates  fields  to  which  no  sewage 
has  been  applied  during  the  warm  season  may  be  reserved 
specially  for  the  reception  of  it  during  the  winter.  These  soils 
would,  therefore,  be  comparatively  dry  and  capable  of  receiving 
6  to  12  inches  of  water  and  of  retaining  it  by  capillarity 
until  warm  weather  could  subject  it  to  organic  purification, 
and  when  crops  could  also  be  made  to  utilize  the  nitrates 
developed  and  other  fertilizers  brought  by  the  water. 


Sewage   Purification  405 

To  handle  the  sewage  in  this  manner,  it  would  be  needful 
to  bring  it  to  the  fields  in  underground  conduits,  and  to  ha've 
the  lands  laid  out  for  flooding  in  checks  of  suitable  size,  sur- 
rounded by  barriers  of  the  desired  height,  but  the  great  diffi- 
culty to  be  met  is  the  amount  of  land  needful  for  such  a 
system.  Allowing  50  gallons  of  sewage  per  day  per  person, 
a  city  of  30,000  would  require  828  acres  to  receive  the  sewage 
during  180  days  if  each  check  were  to  be  flooded  to  a  depth 
of  12  inches. 


THE     PROCESS     OF     SEWAGE     PURIFICATION     BY    IRRI- 
GATION   OR     INTERMITTENT     FILTRATION 

The  extremely  careful  and  extended  investigations  con- 
ducted by  the  State  Board  of  Health  at  Lawrence,  Mass.,  begun 
in  1888  arid  still  in  progress,  have  shown  that  the  purifying 
of  sewage  as  it  passes  slowly  over  the  surface  of  sand  grains 
freely  exposed  to  contained  air,  is  the  result  of  bacterial  growth, 
and  that  when  these  germs  are  not  present  the  sewage  comes 
through  the  filter  as  impure  as  it  went  in  so  far  as  its  dangerous 
nitrogen  compounds  are  concerned.  But  if  it  is  allowed  to 
pass  through  slowly  enough  in  the  presence  of  an  abundance 
of  air,  the  water  emerges  with  so  nearly  all  the  nitrogen  com- 
pounds converted  into  nitrates  that  it  is  as  free  from  them 
as  the  purest  spring  water. 

The  essential  condition  is  that  an  inch  or  two  of  water 
shall  be  spread  out  over  the  surface  of  the  soil  grains  in 
enough  of  the  upper  soil,  where  free  oxygen  may  gain  access 
to  the  colonies  of  niter-forming  germs  which  multiply  there 
and  feed  upon  the  organic  nitrogen  in  the  water,  if  only 
there  is  an  abundance  of  free  oxygen  to  meet  their  other 
needs.  When  a  new  quantity  of  water  is  added  to  the  soil, 
the  purified  layer  is  swept  downward  by  the  new  supply, 
which  at  the  same  time  drags  in  after  it  a  fresh  supply  of 
air,  and  thus  the  work  goes  on. 

If   the  sewage  water  is  added  too  rapidly,  before   the   germs 


406  Irrigation   and   Drainage 

have  completely  used  up  the  organic  nitrugen,  then  it  will  be 
only  partly  purified  ;  or  if  the  flow  over  the  field  is  made  con- 
tinuous, then  the  supply  of  oxygen  in  the  soil  becomes  so 
small  that  the  germs  are  unable  to  carry  forward  the  work, 
and  organic  nitrogen  passes  through  largely  unchanged  and 
liable  to  become  the  food  in  drinking  water  of  other  but 
dangerous  forms. 


SOILS     BEST     SUITED     TO     SEWAGE     IRRIGATION 

In  humid  climates,  where  the  rainfall  is  both  frequent 
and  abundant,  the  lighter  loams  and  sandy  soils  are  best 
suited  to  this  type  of  irrigation,  because  upon  them  there  is  less 
danger  of  water -logging.  It  should  be  understood,  however, 
that  from  the  agricultural  standpoint  sewage  may  be  applied 
to  any  soil,  provided  it  is  not  used  in  too  large  quantities  or  too 
continuously  ;  but  as  the  sandy  soils  are  usually  more  in  need 
of  artificial  fertilization,  and  at  the  same  time  '  likely  to  be 
deficient  in  water,  they  are  preeminently  suited  to  this  use,  and 
wiH  usually  be  chosen  by  city  authorities  when  they  are  avail- 
able, but  simply  because  a  smaller  number  of  acres  will  answer 
the  purpose  and  the  cost  of  the  plant  be  less. 

The  agricultural  value  of  sewage  when  properly  applied  to 
land  has  been  so  thoroughly  demonstrated  under  so  many  condi- 
tions of  soil  and  climate  that  there  can  no  longer  be  any  doubt  as 
to  the  desirability  of  its  use  if  the  expense  of  getting  it  to  the 
land  were  eliminated,  and  it  would  appear  that  lands  enough  in 
the  vicinity  of  most  cities  could  profitably  receive  and  use  the 
sewage  if  only  it  were  led  to  them. 


DESIRABILITY    OF     WIDER    AGRICULTURAL     USE     OF 
SEWAGE     IN     IRRIGATION 

In  countries  like  Italy,  where  there  are  extensive  canal 
systems'  largely  used  for  irrigation,  it  would  appear  that  sewage 
disposal  by  irrigation  should  become  the  general  practice,  pro- 


Agricultural    Use   of  Sewage 


407 


vided  the  canals  are  carrying  constantly  a  sufficient  volume  of 
water  to  make  the  needful  dilution.  The  disposal  of  the  sewage 
of  the  city  of  Milan  in  this-  manner  has  already  been  referred  to 
as  extremely  satisfactory  from  the  agricultural  point  of  view. 

In  speaking  of  the  opportunities  for  and  the  desirability  of 
improving  sandy  lands  in  various  parts  of  the  eastern  United 
States  and  in  the  South  by  silting,  it  was  pointed  out  that  many 


Fig.  125.    Instruction  of  practical  gardeners  in  garden  irrigation. 

hundreds  of  square  miles  of  now  nearly  worthless  lands  could  be 
reclaimed  by  methods  of  irrigation,  and  wherever  this  shall  be 
undertaken  the  disposal  of  the  sewage  of  the  same  sections 
through  the  canal  waters  could  not  fail  to  be  of  great  advantage 
to  the  lands  when  applied  either  in  winter  or  in  summer. 

Outside  the  walls  of  the  city  of  Paris,  on  the  once  nearly 
worthless  gravelly  sands  of  the  Seine,  is  located  a  garden  whose 
sign  is  represented  in  Fig.  125,  where,  in  the  midst  of  a  district 


408 


Irrigation 


Drainage 


devoted  to  sewage  irrigation,  an  effort  is  being  made  to  teach  in 
a  concrete  way  how  thoroughly  purified  sewage  water  may  be 
made  by  irrigation,  and  what  luxuriant  growths  may  spring  from 
nearly  sterile  sands.  Fig.  126  is  a  view  within  the  garden, 
where  grapes  are  growing  on  the  left,  with  dwarf  pears  and 
apples  on  the  right,  while  in  the  center  is  a  trench  of  water 
cress  grown  for  market  in  filtered  sewage,  the  trench  being  at 
the  foot  of  one  of  the  drainage  lines  leading  the  filtered  water 


Fig.  126.     Sewage  irrigation,  model  garden,  Paris. 

to  the  Seine.  So  clear  was  this  water  that  it  had  the  sparkling 
brilliancy  of  that  from  the  purest  springs,  and  outside  the 
garden  women  and  children  came  with  their  buckets  and  filled 
them  for  use  at  home.  Inside,  the  superintendent  keeps  a  glass, 
and  insists  that  every  visitor  shall  taste  and  convince  himself 
how  sweet  and  pure  the  water  is.  Here  and  further  out,  at 
Gennevilliers,  the  lands  are  laid  out  and  divided  much  like 
village  lots,  where  homes,  with  their  vegetable,  fruit  and  flower 


Sewage  for    Garden   Irrigation  409 

gardens,  are  being  established,  and  sewage  water  was  handled 
there  in  1895  by  small  gardeners  with  great  skill  and  profit. 
The  lands  are  held  at  $1,000  per  acre,  and  rent  at  a  high  price. 
The  sewage  for  irrigation  is  carried  beneath  the  surface  in 
closed  pipes,  which  are  provided  with  a  system  of  hydrants  for- 
taking  out  the  water  where  needed,  and  Fig.  127  shows  one  of 
these,  while  Fig.  128  is  taken  at  the  same  place,  standing  at 
the  hydrant  and  looking  down  the  open  ditch  leading  the 
water  to  gardens  and  orchards,  where  it  is  to  be  used. 
Flowers,  garden  vegetables  and  fruits  were  growing  upon  these 
grounds  in  great  luxuriance  for  the  city  markets.  If  such 
results  as  these  can  be  secured  in  France,  why  should  not  the 
philanthropic  zeal  of  Greater  New  York  join  with  the  capital 
of  that  city  and  lead  a  portion  of  the  water  of  the  higher 
lands,  together  with  the  sewage  of  the  inland  towns  and  cities, 
which  is  now  polluting  the  streams,  down  upon  the  flat  New 
Jersey  sands  and  convert  them  into  gardens  of  industry  and 
plenty,  where  the  unfortunate  mothers,  with  their  children  now 
in  the  dark  streets,  could  be  helped  to  comfortable  homes  sur- 
rounded by  conditions  which  make  physical,  intellectual  and 
moral  growth  possible. 

CROPS     SUITED    TO    SEWAGE    IRRIGATION 

There  is  no  crop  more  generally  grown  on  sewage  farms 
than  grass,  which  is  fed  green,  as  cited  in  the  cities  of  Leith 
and  Edinburgh  and  at  Milan  ;  as  silage,  as  has  been  done  at 
Croyden  and  ^Nottingham,  or  made  into  hay,  as  at  Preston.  At 
Blackburn  and  at  Croyden,  also,  the  lands  are  extensively  pas- 
tured, at  the  latter  place  by  coach  and  draft  horses  of  the  city 
for  a  season,  to  allow  their  feet  to  recover  from  the  jar  and 
shock  of  stone  pavements. 

In  England  and  in  Italy  very  heavy  crops  of  grass  are 
grown,  yielding  all  the  way  from  40  to  70  tons  per  acre  per 
season.  The  grass  most  extensively  grown  in  Europe  is  the 
Italian  Rye  Grass,  but  it  is  not  permanent,  and  the  land  must 
be  plowed  and  reseeded  every  three  or  four  years  if  heavy 


Fig.  127.     Sewage  hydrant  at  Gennevilliers. 


Fig.  128.     Stone  distributing  canal  leading  from  hydrant  in  Fig.  127. 


Crops  for   Sewage   Irrigation  411 

yields  are  desired.  On  the  Craigentinny  Meadows,  most  of  the 
grasses  are  the  native  forms,  which  soon  crowd  out  the  Rye 
Grass  if  it  is  not  reseeded. 

Both  oats  and  wheat  are  extensively  grown  on  sewage 
land,  but  in  these  cases  the  land  is  usually  only  irrigated  dur- 
ing the  winter.  Potatoes,  turnips  and  mangels,  as  well  as 
cabbage  and  cauliflower,  are  also  grown. 

At  Croyden  and  Preston,  potatoes  are  grown  on  a  large 
scale  on  winter  irrigated  land  and  the  crop  sold  at  auction 
when  mature  at  $60  to  $75  per  acre,  the  purchaser  digging  the 
potatoes.  Fig.  129  shows  a  crop  of  early  potatoes  grown  at 
Croyden  which  sold  in  July  for  £15  per  acre,  and  Fig.  130  is 
a  view  of  the  cement  ditch  in  which  the  water  is  brought  to 
the  fields  from  the  city.  When  summer  irrigation  of  potatoes 
is  practiced  at  Croyden,  the  superintendent  stated  that  he  pre- 
ferred to  use  the  water  only  after  it  had  drained  from  another 
field.  He  also  stated  that  he  thought  the  sewage  water  tended 
to  intensify  the  scab. 

At  Nottingham,  where  much  wheat  is  raised,  this  is  grown 
on  winter  irrigated  land,  but  cabbage,  turnips  and  mangels  are 
irrigated  in  the  summer  as  well  as  winter.  The  cabbages 
raised  here  are  the  large  stock  varieties,  planted  in  rows  4 
feet  apart  with  the  plants  3  feet  apart  in  the  row,  and 
enormous  yields  are  secured  of  the  vegetables  named  and  fed 
to  a  herd  of  from  800  to  1,000  cows. 

At  Gennevilliers,  nearly  all  varieties  of  garden  truck  were 
being  raised  with  great  success,  and  there  were  orchards  of 
pears,  prunes  and  apples,  and  vineyards  of  grapes,  heavily 
loaded  with  fruit  in  August  of  1895.  So,  too,  at  Berlin, 
mangels,  turnips,  celery,  onions,  parsnips,  beans,  cabbage  and 
cauliflower  were  raised  on  their  sewage  farms. 

While  the  general  practice  in  Europe  seems  to  be  to  favor 
summer  irrigation  of  grass,  and  winter  irrigation  for  small 
grains  and  cultivated  crops  generally,  it  appears  clear  that 
therp  a~e  few  if  any  crops  to  which  sewage  may  not  be  applied 
with  great  advantage  if  only  rational  practice  is  followed. 

It  will  be  readily  understood  that  where  fertilization  is  the 


Pig.  129.    Harvesting  early  potatoes  on  Croyden  sewage  farm,  England. 


Fig.  130.    Cement  canal  at  sewage  farm,  Croyden,  England. 


Sewage   Irrigation   and   Healthfulness          418 

main  object,  together  with,  the  disposal  of  the  sewage,  lands 
may  be  irrigated  at  once  after  the  removal  of  a  crop,  such  as 
wheat  or  any  of  the  small  grains,  so  that  there  may  be  ample 
latitude  for  distributing  the  water  at  almost  any  season  of 
the  year. 

In  climates  where  the  winters  are  severe,  it  is  necessary  to 
apply  the  sewage  to  land  not  in  grass  or  other  perennial  crop, 
as  the  freezing  of  thick  coats  of  ice  over  the  meadows  is  quite 
certain  to  greatly  injure  if  not  kill  the  grass.  Another  point 
which  the  agriculturist  should  keep  in  mind  and  guard  against, 
is  the  application  of  sewage  to  crops  in  too  concentrated  a  form, 
and  especially  should  it  be  so  much  diluted  or  strained  that  the 
sludge  will  not  collect  upon  the  surface  in  sufficient  quantity 
to  close  up  the  pores  of  the  soil  and  interfere  with  proper 
aeration. 

INFLUENCE    OF     SEWAGE     IRRIGATION    UPON 
THE    HEALTH 

Reference  has  been  made  to  experiments  and  observations 
which  show  that  the  feeding  of  grass  from  sewage  farms  to 
milch  cows  produces  no  injurious  effects  upon  the  milk  itself. 
The  late  Colonel  Waring  states  that  the  health  of  the  people 
living  upon  the  sewage  lands  at  Gennevilliers  is  generally  excel- 
lent, and  that  "even  in  1882,  when  there  was  a  cruel  epidemic 
of  typhoid  fever  in  Paris,  there  was  none  here."  He  further 
says  :  "  If  there  is  still  room  for  doubt  on  any  point,  it  is  as 
to  the  character  of  the  few  bacteria  which  escape  the  action  of 
the  process  employed,  and  are  found  in  the  effluent.  It  is  not 
known  that  disease  germs  exist  among  these,  and  it  is  altogether 
probable  that  they  do  not.  So  far  as  these  organisms  are 
understood,  it  is  thought  that  they  cannot  withstand  the 
destructive  activity  of  the  oxidizing  and  nitrifying  organisms 
which  are  always  present,  and  it  is  believed  that  only  these 
hardier  organisms  exist  in  the  effluent  of  land -purification  works. 
Certain  it  is  that  no  instance  has  been  reported  where  con- 
tagion was  carried  by  such  effluents,  and  experience  at  Genne- 


414  Irrigation   and   Drainage 

villiers  has  shown  that  typhoid  fever  and  cholera,   when  rife  in 
Paris,  were  completely  arrested  at  the  irrigation  fields." 

"  In  the  Massachusetts  table  of  comparison  of  the  purified 
effluent  of  seven  sewage  filters  and  the  waters  of  seven  wells 
used  for  drinking  by  many  persons,  it  is  shown  that  there 
were  three  and  one -half  times  ar*  many  bacteria  in  the  wel) 
waters  as  in  the  effluents." 


PART  II 
FARM   DRAINAGE 


CHAPTER   XII 

PRINCIPLES   OF  DRAINAGE 

IT  has  been  pointed  out  that  if  all  of  the  irri- 
gated lands  of  the  world  were  brought  together  in 
a  solid  body,  they  would  scarcely  aggregate  more  than 
an  area  500  miles  on  a  side,  or  250,000  square  miles. 
But  Professor  Shaler  estimates  that  in  the  United  States 
alone,  east  of  the  100th  meridian,  there  are  more 
than  100,000  square  miles  of  swamp  lands.  Some  of 
these  have  been  reclaimed  by  drainage,  and  the  great 
majority  of  them  could  be,  if  the  expense  of  the 
reclamation  would  be  warranted  by  the  returns  which 
would  follow.  In  the  Canadas,  in  Europe,  and  in 
other  portions  of  the  world,  also,  there  are  vast  areas 
of  land,  when  measured  in  the  aggregate,  which 
must  be  drained  before  they  can  become  agricul- 
turally productive.  Hence  the  principles  of  land  drain- 
age, like  those  of  irrigation,  must  be  clearly  under- 
stood by  those  who  are  concerning  themselves  with 

(415) 


416  Irrigation   and   Drainage 

the   great    world   problems    of    better    homes  and   all- 
which  these  mean. 

Further  than  this,  on  account  of  the  fact  that  a 
large  majority  of  swamp  lauds  and  lands  which  may 
be  improved  by  drainage  are  not  massed  together,  but 
are  scattered  broadly  in  small  tracts,  so  related  to 
the  higher  and  better -drained  lands  that  these  must 
often  be  improved  in  order  to  work  the  others  to 
the  best  advantage,  the  principles  of  farm  drainage 
become  a  matter  of  great  importance  to  a  large  pro- 
portion of  the  rural  population,  and  through  good 
roads  to  the  people  of  cities  as  well. 

THE    NECESSITY    FOR     DRAINAGE 

The  first  and  most  fundamental  necessity  for  land 
drainage,  as  has  been  pointed  out  in  discussing 
alkali  soils,  is  the  removal  of  the  more  soluble  salts 
formed  by  the  decay  of  rock  and  organic  matter, 
because  too  strong  a  solution  of  salts  in  the  soil  water 
is  fatal  to  the  growth  of  vegetation,  and  gives  rise 
to  the  alkali  lands.  So  long  as  there  is  sufficient 
leaching  to  hold  the  soluble  salts  down  to  small  per- 
centages, so  that  neither  plasmolytic  nor  toxic  effects 
result,  then  the  first  imperative  demand  for  thor- 
ough drainage  in  all  soils  is  met. 

The  second  imperative  demand  for  drainage  is  to 
prevent  a  stagnation  of  the  soil  water,  which  means, 
to  avoid  the  exhaustion  of  oxygen  from  the  air  in 
the  soil  water  and  in  the  spaces  not  occupied  by 
water,  because  an  abundance  of  free  oxygen  in  the 


ity  for  Drainage  417 

soil  is  a  fundamental  necessity  to  plant  life,  and 
thorough  drainage  secures  this. 

The  third  demand  for  drainage  is  to  render  the 
soil  sufficiently  firm  and  solid  to  permit  the  field  or 
road  to  be  moved  over  without  difficulty  or  incon- 
venience. If  the  spaces  between  the  soil  grains  are 
completely  filled  with  water,  then  there  is  no  surface 
tension,  and  so  only  a  slight  friction  to  bind  the 
grains  together,  and  hence  they  move  so  easily  upon 
one  another  as  to  be  unable  to  sustain  much  weight, 
and  the  horse  or  wagon  mires. 

Everyone  is  familiar  with  the  hard  surface  pos- 
sessed by  wet  beach  sand,  from  which  the  water  has 
just  withdrawn,  and  how  yielding  it  is  when  under 
water  and  also  when  it  becomes  dry.  In  the  first 
case,  the  sand  grains  are  bound  together  by  the  thin 
films  of  water  which  surround  them  ;  in  the  second 
case,  there  is  no  free  water  surface  between  the  grains, 
and  the  sand  tends  simply  to  float  and  so  moves 
easily ;  while  in  the  third  case,  when  the  sand  is 
dry,  the  binding  water  films  have  either  drained 
away  or  have  been  lost  by  evaporation,  hence  there 
is  nothing  to  hold  the  grains  together. 

The  hard,  firm  character  of  a  clay  soil  when  it 
loses  its  moisture  is  due  to  the  fact  that  the  grains 
are  so  small  and  so  close  together  that  the  little 
material  which  is  held  in  solution  in  the  soil  water 
cements  them  together  when  dry.  Were  the  grains 
large  like  those  of  the  sands,  with  few  of  the  fine 
particles  between  them,  the  contact  areas  would  be  so 
few  and  so  small  that  little  binding  could  result. 


418  Irrigation   and  Drainage 

THE    DEMANDS    FOR    AIE    IN    THE    SOIL 

It  must  ever  be  kept  in  mind  that  an  abundance  of 
free  oxygen  in  the  soil  is  as  indispensable  to  the  life 
of  the  plant  as  it  is  to  that  of  an  animal.  The 
germinating  seeds  must  have  it,  or  they  rot  in  the 
soil  ;  the  roots  of  plants  must  have  it  to  enable 
them  to  do  their  work ;  and  the  vast  army  of 
soil  bacteria,  which  change  the  nitrogen  of  decaying 
organic  matter  into  nitric  acid,  which  is  the  chief 
nitrogen  supply  for  most  higher  plants,  must  have 
it  or  they  cannot  thrive.  Again,  those  very  impor- 
tant germs  which  live  on  the  roots  of  clover  and 
other  allied  plants,  and  which  are  the  chief  source 
of  the  organic  nitrogen  of  the  world,  must  have  an 
ample  supply  of  both  free  oxygen  and  free  nitrogen 
in  the  soil,  or  they  are  unable  to  accomplish  their 
task. 

Again,  there  lives  in  all  fertile  soils  a  class  of 
germs  which  have  the  power  of  breaking  down 
nitrates,  or  even  organic  matter,  to  supply  them- 
selves with  oxygen  whenever  the  conditions  are  such 
that  the  soil  does  not  contain  enough  to  meet  their 
needs.  But  when  these  germs  are  forced  to  do  this, 
as  happens  in  a  water -logged  or  poorly  drained  soil, 
the  nitrogen  of  the  soil  nitrates  and  of  organic 
matter  is  liberated  in  the  form  of  free  nitrogen 
gas,  and  hence  the  soil  may  thus  be  depleted  of 
this  most  expensive  ingredient  of  plant -food  wherever 
proper  drainage  does  not  exist. 

Finally,    many     purely     chemical     changes    taking 


Drainage    Ventilates   the   Soil  419 

place  in  the  soil,  which  are  essential  to  its  fer- 
tility, demand  both  free  oxygen  and  carbon  dioxide, 
so  that  here  is  another  need  for  good  drainage,  in 
order  that  air  may  enter  the  ground  in  abundance. 

HOW    DRAINAGE    VENTILATES    THE    SOIL 

Where  standing  water  would  be  found  in  holes 
sunk  18  to  24  inches  below  the  surface,  capillarity 
would  hold  the  pores  of  a  fine  soil  so  nearly  full 
of  water  to  the  top  of  the  ground  that  there  would 
be  little  room  left  for  air  to  enter ;  but  when  the 
ground  water  is  permanently  lowered  three  or  four 
feet,  as  is  done  by  underdraining,  the  roots  of  plants 
penetrate  the  soil  more  deeply,  and,  as  they  die  and 
decay,  leave  passageways  leading  to  the  surface,  into 
and  out  of  which  the  air  readily  moves.  Earth- 
worms, ants,  and  other  burrowing  animals  penetrate 
the  ground  more  deeply,  and  open  other  ventilating 
flues  of  much  larger  magnitude  than  those  left  by 
the  roots  of  plants,  and  so  greatly  increase  soil  ven- 
tilation as  a  result  of  drainage. 

Then,  again,  when  the  deeper  clays  dry  out,  as 
they  will  after  underdrainage,  shrinkage  checks  form 
in  them  in  great  numbers,  opening  tiny  fissures 
through  which  the  air  moves  more  freely  with  every 
change  of  temperature  and  pressure  of  the  atmos- 
phere above.  With  the  deeper  and  more  thorough 
penetration  of  soil -air,  carrying  with  it  the  car- 
bonic acid  developed  near  the  surface,  there  begins, 
through  the  agency  of  the  soil  water,  a  solution  of 


420  Irrigation  and  Drainage 

the  lime  which  in  its  turn  tends  to  force  the  fine 
clay  particles  into  larger  compound  clusters,  thus  ren- 
dering the  soil  more  open,  and  hence  better  drained, 
better  ventilated,  and  at  the  same  time  better  and 
more  thoroughly  occupied  by  the  roots  of  plants. 

But  all  of  these  changes,  which  result  directly 
from  lowering  the  ground -water  surface,  are  only 
means  which  make  underdrainage  more  effective  in 
ventilating  the  soil.  In  an  underdrained  field,  where 
lines  of  tile  are  laid  3  to  4  feet  deep  and  50  to  100 
feet  apart,  there  is  provided  a  very  effective  system 
of  soil  ventilation  as  well  as  of  drainage  ;  for  with 
every  fall  of  the  barometer  and  rise  of  soil  tempera- 
ture, some  of  the  deeper  soil -air  expands  and  drains 
away  through  the  lines  of  tile.  Then,  when  the 
barometer  rises  again,  or  when  the  soil  temperature 
falls,  a  volume  of  air  equal  to  that  which  left  the 
soil  under  the  other  conditions  now  enters  it  again, 
not  only  through  the  surface  of  the  ground,  but 
also  through  the  tile  drains.  It  is  thus  seen  that 
a  deep,  well -laid  system  of  tile  drains  permits  the 
free  oxygen  of  the  air  to  reach  the  roots  of  plants 
both  from  above  and  below.  Under  these  condi- 
tions, the  roots  of  crops  are  better  supplied  with 
oxygen  ;  nitrates  develop  faster  and  deeper  in  the 
soil  ;  there  is  less  occasion  for  denitrification  to  set 
in,  and  so  larger  yields  result. 

When  deep  underdrainage  has  permitted  the  roots 
of  plants  to  penetrate  the  soil  from  3  to  4  feet  and 
there  withdraw  moisture,  this  action  on  their  part 
becomes  a  means  for  drawing  air  into  the  ground, 


Drainage    Ventilates   the   Soil  421 

both  from  the  surface  and  through  the  tile  drains, 
because  the  removal  of  the  soil  water  by  the  roots 
leaves  an  open  space,  which  must  be  filled  with  air 
so  far  as  capillarity  fails  to  do  it  with  water,  and 
hence  deep  root  feeding  means  deep  soil  ventilation. 

Then,  again,  when  heavy  rains  fall  which  move 
downward  through  the  soil,  they  displace  both  the 
air  and  the  water  previously  there,  crowding  them 
forward  into  the  drains,  and  then  draw  in  after  them 
a  fresh  supply  from  above.  But  only  on  well- 
drained  soils  is  this  action  marked  and  helpful. 

A  word  should  be  said  here  regarding  the  value 
of  clover  and  alfalfa  as  soil  ventilators,  for  by  their 
thicker,  stronger  roots  they  set  the  soil  aside  more  than 
most  other  cultivated  crops  do,  and  when  these  roots 
decay  the  soil  is  left  better  aerated  and  better 
drained.  Further  than  this,  the  roots  of  these  legu- 
minous plants  remove  from  the  soil  both  free  oxygen 
and  free  nitrogen,  and  in  so  far  as  they  do  this  with- 
out returning  an  equal  volume  of  another  gas,  their 
action  tends  to  develop  a  vacuum  which  must-  be 
filled  by  bringing  in  a  fresh  supply  from  without. 

TOO  THOROUGH  AERATION  OP  THE  SOIL 

There  may  be  too  strong  and  rapid  changes  of 
soil-air,  just  as  there  may  be  too  rapid  and  complete 
drainage.  If  the  air  enters  a  rich,  damp  soil  too 
rapidly,  there  is  so  strong  a  development  of  nitrates 
that  the  humus  and  other  organic  nitrogen  are  quickly 
changed  into  the  soluble  forms,  and  rapidly  leach 


422  Irrigation  and  Drainage 

away.  It  is  in  this  manner  that  coarse,  sandy  soils 
are  impoverished,  and  their  lack  of  productiveness 
is  often  due  quite  as  much  to  too  thorough  ventilation 
as  to  too  complete  drainage  ;  and  in  handling  these 
soils  the  utmost  care  should  be  exercised  to  keep 
the  content  of  humus  high,  the  moisture  plenty,  ana 
the  winds  from  drifting  away  the  finest  dust  particles, 
because  all  of  these  tend  to  close  up  the  pores,  giving 
the  soil  a  texture  which  diminishes  the  amount  of 
ventilation. 

DRAINAGE     INCREASES    THE    AVAILABLE     SUPPLY    OP 
SOIL    MOISTURE    FOR    CROPS 

When  soils  are  poorly  drained  during  spring  and 
early  summer,  the  root  system  of  the  various  crops 
is  forced  to  develop  near  the  surface,  and  if  this  is 
the  case  until  the  demands  for  moisture  become  large, 
the  soil  in  which  the  roots  are  confined  becomes  very 
dry,  because  capillarity  brings  the  water  up  from 
below  too  slowly  to  meet  the  demand. 

It  is  a  familiar  fact  that  a  damp  cloth  is  much 
better  to  remove  water  from  the  floor  than  a  dry  one, 
and  the  same  is  true  of  soils  ;  water  rises  by  capil- 
larity in  them  when  quite  moist  much  faster  than 
when  they  become  dry,  and  so  it  is  a  matter  of  the 
greatest  moment  to  keep  the  surface  soil,  beneath  the 
mulch,  as  damp  as  the  best  conditions  for  growth 
will  permit.  When  the  deeper  soil  in  the  spring  and 
early  summer  is  well  drained,  and  the  roots  of  the 
crop  penetrate  it,  they  not  only  find  themselves  closer 


Drainage   Increases   Available   Moisture         423 

to  the  ground  water  supply,  but  not  so  many  roots 
are  forced  to  take  the  moisture  near  the  surface,  and 
hence  for  this  reason  capillarity  is  better  able  to  hold 
the  water  content  up  to  the  saturation  needed. 

With  the  soil  near  the  surface  moist,  where  nitrates 
are  mostly  formed,  a  better  supply  of  these  is  kept 
up,  while  at  the  same  time  there  is  moisture  enough 
to  hold  them  in  solution  and  to  enable  the  roots 
to  obtain  them.  When  other  roots  are  deeper  in  the 
ground,  these  may  chiefly  draw  water  to  meet  the 
necessary  evaporation  wrhich  goes  on  in  the  leaves, 
and  thus  reserve  the  surface  moisture  for  developing 
plant -food  and  giving  it  to  the  plant.  In  this  way 
it  happens  that  crops  suffer  less  in  times  of  drought 
on  well -drained,  heavy  soils  than  they  do  on  the  same 
soils  not  drained. 

SOIL    MADE    WARMER    BY    DRAINAGE 

There  is  no  cause  so  effective  in  maintaining  a  low 
temperature  of  the  soil  in  the  spring  as  the  water 
which  it  contains,  and  which  may  be  evaporating  from 
its  surface.  One  reason  for  this  influence  is  found 
in  the  fact  that  more  heat  is  required  to  change  the 
temperature  of  a  pound  of  water  one  degree  than  the 
same  weight  of  almost  any  other  substance.  Thus, 
while  100  units  of  heat  must  be  used  to  warm  100 
pounds  of  water  from  32°  F.  to  33°  F.,  only  19.09 
units  are  required  to  raise  the  temperature  of  the 
same  weight  of  dry  sand,  and  22.43  units  an  equal 
weight  of  pure  clay  through  the  same  range  of 


424  Irrigation  and  Drainage 

temperature.  Stated  in  another  way,  the  amount  of 
sunshine  which  will  warm  a  given  weight  of  water 
10°  F.  will  raise  the  temperature  of  an  equal  weight 
of  dry  sand  52.38°  F.,  clay  44.58°  and  humus  22.6°. 
It  is  plain,  therefore,  that  very  wet  soils  must  warm 
in  the  sun  more  slowly  because  the  water  which  they 
contain  tends  to  hold  the  temperature  down. 

The  chief  cause,  however,  which  makes  a  wet, 
undrained  soil  colder  than  the  better  drained  one,  is 
the  cooling  effect  which  results  from  the  more  rapid 
evaporation  of  water  from  the  wetter  soil  surface. 
When  -the  bulb  of  one  of  two  similar  thermometers 
is  covered  with  a  jacket  of  muslin  moistened  with 
pure  water,  and  the  two  are  swung  side  by  side  in 
a  dry  air,  it  will  often  be  observed  that  the  bulb  bear- 
ing the  moist  cloth  will  have  its  temperature  lowered 
as  much  as  20°  F.  by  the  cooling  effect  of  evaporating 
water.  So,  too,  when  water  evaporates  from  any  sur- 
face, no  matter  what,  its  temperature  is  lowered  in 
proportion  to  the  rate  at  which  evaporation  is  taking 
place.  The  teakettle  boiling  over  the  hot  fire  has 
its  temperature  constantly  held  down  to  212°  by  the 
rapid  evaporation  of  water,  although  the  heat  of  the 
fire  playing  upon  it  is  very  many  degrees  hotter. 

It  is  the  same  way  with  a  wet  soil  through  which 
water  is  continually  brought  to  the  surface  as  rapidly 
as  it  can  be  evaporated  in  the  heat  of  the  sunshine. 
The  loss  of  the  water  in  this  way  necessarily  holds 
the  temperature  down,  and  the  lower  the  more  rapidly 
the  evaporation  takes  place.  The  following  table* 

The  Soil,  p.  227. 


Importance   of  Soil    Warmth  425 

shows   the    observed    difference    in    temperature   of    a 
drained  and  an  undrained  soil  : 

Temperature 

Condition  of        Temp,  of    of  drained  of  undrained  Differ- 
Date        Time  weather  air  soil  soil  ence 


April  24       -  °UWrS        60'5°  F'  66"5°  54-00°          12'50° 


April253303ptom  .    C10U<ea'stWwhidriSk      64'°°  F"  70-°°  58-00°         12-00° 


April  26     l'30^0     C10Ugrern*o;nallth6     45.0°  F.  50.0°  44.00°  6.00° 

April  27    U0^    °\"^  s"  WUbriske'  53-°°  F"  55'°°  50'75°  4'25° 

A      •!  <>Q      7  to        Cloudy  and  sunshine,  4c  no  p  4.7  n°  AA  t\n°  9  nn° 

April  28  g30  a  m       wind  N.  W.  brisk      45'°    F"  4*'BO 

The  difference  in  the  rate  of  evaporation  from 
clayey  soil  and  sandy  soil,  when  both  are  well 
drained,  will  often  be  enough  to  leave  the  clay 
soil  7°  F.  colder  in  the  surface  foot  and  5°  colder 
in  the  second  and  third  feet  below  the  surface. 


IMPORTANCE    OF    SOIL    WARMTH 

Ebermayer  concluded  from  his  observations  that 
relatively  little  growth  can  take  place  with  most  cul- 
tivated crops  until  after  the  soil  temperature  has 
been  carried  above  45°  to  48°  F.,  and  the  maximum 
results  are  reached  only  after  a  temperature  of  68° 
to  70°  has  been  attained. 

Sachs  showed  that  both  pumpkin  and  tobacco 
plants  wilted,  even  at  night  and  with  an  abundance 
of  moisture  in  the  soil,  when  its  temperature  fell 
much  below  55°  F.,  the  osmotic  pressure  being  then 
too  feeble  to  maintain  a  sufficient  movement  of  soil 
moisture  to  keep  the  plant  cells  turgid.  Phenomena 


426 


Irrigation  and  Drainage 


similar  to  this  are  often  observed  early  in  the  spring, 
when  leaves  are  just  unfolding.  A  strong  drying 
wind  on  a  cool  day,  with  the  soil  also  cold,  withers 
the  leaves  much  as  if  they  had  been  frosted. 

The  germination  of  seed  is  very  much  influenced 
by  the  temperature  of  the  soil,  maize  requiring  16 
days  to  appear  above  the  ground  when  the  soil  tem- 
perature is  60°  F.,  or  below,  when  if  the  warmth  is 
72°  or  above,  3  days  or  less  will  do  the  same  work, 
besides  giving  much  stronger  plants.  These  effects 


Fig.  131.    Influence  of  soil  temperature  on  the  rate  of  germination  of  maize. 

of  soil  temperature  are  clearly  demonstrated  in  Fig. 
131.  Indeed,  it  will  often  happen  that  when  seed 
of  rather  low  vitality  is  planted  in  a  soil  a  little  too 
cold,  germination  will  not  take  place  at  all,  or  if  it 


Importance   of  Soil    Warmth  427 

does,  the  plants  are  so  much  enfeebled  that  only  a 
slow  growth  results  afterward. 

In  the  early  part  of  the  season,  when  ground  is 
being  fitted  for  seeding,  it  should  ever  be  kept  in 
mind  that  one  of  the  chief  objects  of  the  early  and 
thorough  tillage  is  to  develop  an  abundance  of 
nitrates  in  the  soil  for  the  use  of  the  crop.  But 
this  is  done  by  making  the  soil  warmer,  and  by 
introducing  an  abundance  of  air  into  it  when  there 
is  a  good  supply  of  moisture  associated  with  the 
humus  upon  which  the  niter  germs  feed.  These 
germs  cease  to  develop  niter  from  humus  when  the 
soil  temperature  drops  to  41°  F.  ;  the  action  is  only 
barely  appreciable  at  54°  F.,  and  it  reaches  its  maxi- 
mum rate  only  at  a  temperature  of  98°  F. 

Now,  the  early,  deep  stirring  of  the  soil  in  the 
spring  prevents  the  moisture  from  coming  up  from 
below,  and  so  lessens  the  rate  of  evaporation  ;  this 
allows  the  soil  to  become  warmer.  Besides  the  heat  is 
not  conducted  as  rapidly  downward  when  the  soil  is 
loose  ;  this  makes  the  stirred,  well  ventilated  portion 
warmer  also,  so  that  for  the  germination  of  the  seed 
and  for  the  development  of  plant -food,  deep  early 
tillage  is  very  important.  It  is  plain,  also,  that  the 
well -drained  field  not  only  can  be  tilled  earlier  and 
deeper,  but  will  also  have  the  soil  warmer  and  richer, 
for  the  reasons  just  stated. 

For  the  same  reason  that  sugar  dissolves  faster  in 
warm  than  in  cold  water,  so  the  ash  ingredients  of 
plant -food  are  dissolved  faster,  and  stronger  solutions 
of  them  are  formed  in  the  warm  than  in  the  cold 


428  Irrigation  and  Drainage 

soils,  and  hence   land   drainage  may  be    beneficial   to 
crop  growth  in  this  manner. 

CONDITIONS     UNDER    WHICH     LAND     DRAINAGE 
BECOMES     DESIRABLE 

It  must  be  kept  ever  in  mind  that  all  lands,  of 
whatever  kind,  require  draining,  but  it  is  extremely 
fortunate  that  for  most  lands  this  is  done  by  the 
natural  methods  of  percolation  and  underflow  of 
ground  water. 

The  cases  in  which  it  becomes  desirable  to  supple- 
ment the  methods  of  natural  drainage  fall  into  five 
classes  :  first,  those  comparatively  flat  lands  or  basins 
upon  which  the  surface  waters  from  surrounding 
higher  land  frequently  collect ;  second,  areas  border- 
ing higher  lands,  whose  structure  is  such  as  to  permit 
the  underflow  of  the  ground  water  from  the  adjacent 
regions  to  rise  from  beneath,  thus  keeping  the  soil 
too  wet  ;  third,  lands  regularly  inundated  by  the  rise 
of  the  tides,  or  which  would  be  if  not  shut  off  by 
dykes  ;  fourth,  those  extremely  flat  lands  which  are 
underlaid  by  considerable  thicknesses  of  close,  heavy 
beds  of  clay,  through  which  water  does  not  readily 
percolate,  and  which  lie  very  close  to  the  surface,  so 
that  the  clays  become  the  subsoil  of  the  fields,  and 
fifth,  lands  like  rice- fields,  water-meadows  and  cran- 
berry marshes,  to  which  water  is  applied  by  irrigation 
in  excessive  quantities.  It  may  also  be  found  desir- 
able on  some  irrigated  lands  to  introduce  drainage  to 
remove  injurious  salts,  as  described  under  alkalies. 


Origin   of  Ground    Water  429 

THE    ORIGIN   OF    GROUND    WATER    AND    ITS 
RELATION    TO    THE    SURFACE 

To  understand  the  laws  governing  the  flow  of 
water  into  tile  drains  and  ditches,  it  is  necessary  to 
know  how  the  flow  into  streams  and  lakes  takes 
place,  and  how  the  surface  of  the  water  in  the 
ground  is  related  to  that  in  the  streams  and  lakes 
into  which  it  is  continually  draining. 

The  rains  which  fall  upon  the  surface  tend,  first 
of  all,  to  sink  vertically  downward  until  they  reach 
the  level  at  which  the  pores  in  the  soil  or  rock  are 
completely  filled  with  water.  There  are  no  soils  and 
very  few  rocks  through  which  there  can  be  abso- 
lutely no  flow,  but  the  downward  percolation  is  very 
much  slower  in  some  than  it  is  in  others.  This 
being  true,  everywhere  beneath  the  land  surface  a 
place  may  be  reached  where  the  pores  are  filled  with 
water,  and  the  level  at  which  this  occurs  is  called 
the  ground -water  surface. 

This  ground -water  surface  is  seldom  horizontal, 
but  usually  rises  and  falls  much  as  does  that  of  the 
ground  above  it,  but  with  gradients  less  steep.  In 
Fig.  132  is  represented  a  section  of  land  adjoining  a 
lake,  where  the  differences  in  level  of  the  surface  are 
shown  by  means  of  contour  lines  passing  through  all 
places,  having  the  height  above  the  lake  indicated  by 
the  number  set  in  the  line  ;  while  in  Fig.  133  the 
surface  of  the  ground  water  for  the  same  area  is 
also  indicated  in  like  manner.  The  data  for  the  levels 
of  the  ground  water  were  procured  by  sinking  wells 


Fig.  132.    Contours  of  the  surface  of  the  ground  in  the  vicinity  of  a 
tile-drained  area. 


*  X^N^ 

*""" — iSi£rv~****^  fjC  Q  Qt?V  __^_  \>  \  \  <*  S^  X. 

rnjm&M^  *** 


JTig.  133.    Contours  of  the  level  of  the  ground-water  surface  under  the 
locality  represented  in  Fig.  132. 


432 


Irrigation  and   Drainage 


at  the  places  designated  by  the  small  numbered  cir- 
cles. 

Referring  to  the  two  figures,  it  will  be  observed 
that  there  is  a  marked  tendency  for  the  ground- 
water  surface  to  stand  highest  where  the  level  of  the 
field  is  also  highest,  and  that  there  are  valleys  in  the 
ground -water  surface  beneath  the  valleys  in  the  field. 
It  will  be  seen  that  the  water  rises  as  the  distance 
from  the  lake  increases,  and  that  in  places  it  stands 
10  and  even  20  feet  higher. 

This  distorted  surface  of  the  ground  water  cannot 
be  a  condition  of  rest,  for  gravity  tends  continually  to 
force  a  flow  from  the  higher  toward  the  lower  levels 
along  the  lines  indicated  by  the  arrows  shown  in  Fig. 
133.  Since  the  further  this  water  must  travel  through 
the  soil  to  reach  the  lake  the  more  resistance  it  must 
meet,  it  is  plain  that  a  greater  pressure  will  be  re- 


Fig.  134.    Diagram  of  lines  of  flow  of  water  in  the  drainage  of  a  river  valley. 

quired  to  overcome  this  resistance,  and  hence  the 
water  must  stand  higher  in  the  ground  the  farther  the 
distance  to  the  drainage  outlet.  The  space  enclosed 
by  the  rectangle  in  Fig.  133  is  an  area  which  required 
underdraining  to  fit  it  for  farm  crops,  and  the  reason 
it  did  is  clearly  shown  by  the  contours  of  the  two 


Movements   of  Ground    Water  433 

maps  and  by  the  arrows  representing  the  lines  of 
underflow,  which  concentrate  from  the  surrounding 
higher  lands  to  pass  beneath  this  section  so  near 
the  surface  that  the  strength  of  capillarity  was  suffi- 
cient to  over -saturate  the  soil  above.  The  influence 
of  the  tile  drains  in  lowering  the  surface  of  the 
ground  water  is  plainly  shown  by  the  distance  the 
contours  are  carried  back  from  the  lake  shore,  as  seen 
along  the  line  marked  "tile  drain." 

In  the  case  of  streams  winding  through  valleys, 
the  water  comes  to  them  at  every  point  along  their 
course  by  slow  seepage,  entering  the  channel  through 
the  banks  and  bottom  in  the  manner  represented  in 
the  diagram,  Fig.  134,  where  the  heavily  shaded  por- 
tion represents  the  soil  filled  with  water  and  the  lines 
with  arrow  points  the  direction  of  flow. 

In  Fig.  135  is  represented  the  surface  of  the 
ground  water  in  the  valley  of  the  Los  Angeles  river, 
California.  The  data  for  the  contours  were  procured 
by  sinking  wells  at  the  points  designated  by  the 
heavy  dots.  From  the  map  it  is  clear  that  the  water 
stands  higher  and  higher  above  the  bed  of  the  stream 
as  the  distance  back  increases,  and  that  there  must 
be  a  steady  flow  down  the  valley  and  toward  the 
river,  thus  draining  the  surrounding  country.  Indeed, 
in  a  distance  of  about  11  miles  the  measured  growth 
of  the  Los  Angeles  river  in  1898  was  60  cubic  feet  of 
water  per  second,  and  yet  no  visible  streams  entered, 
the  supply  coming  by  slow  seepage  along  the  banks 
and  bottom  of  the  entire  length  of  the  section 
measured. 


Ground    Water    Gradient  435 

It  will  be  clear,  therefore,  from  the  cases  cited, 
that  wherever  the  moving  sheet  of  ground  water  ap- 
proaches within  capillary  range  of  the  surface  of  the 
ground,  there  the  soil  is  liable  to  be  too  wet  for  crops 
unless  underdrained. 

BATE     AT     WHICH      THE     GROUND -WATER      SURFACE 
RISES    AWAY    FROM    THE     DRAINAGE    OUTLET 

In  well  29  of  Fig.  133,  situated  150  feet  from  the 
lake,  the  water  stood  7.214  feet  above  the  level  of  the 
lake  June  27,  1892,  thus  showing  a  rise  of  1  foot  in 
every  24.4  feet.  At  another  place  in  the  same  locality, 
but  not  shown  in  the  map,  a  well  1,250  feet  from  the 
lake  shows  the  ground -water  surface  to  stand  52  feet 
above,  thus  giving  a  gradient  of  1  foot  in  24  feet. 
Later  in  the  season,  when  the  ground  had  become 
dryer,  the  gradient  at  well  29  became  1  foot  in 
35.86  feet. 

Between  tile  drains  33  feet  apart  and  4  feet  deep, 
laid  within  the  rectangle  of  Fig.  133,  measurement 
showed  the  surface  of  the  water  to  rise  at  the  mean 
rate  of  1  foot  in  25  feet  48  hours  after  a  rainfall  of 
.87  inches,  and  the  shape  of  the  ground -water  surface 
at  the  time  in  question  is  represented  in  Fig.  137. 
Of  course,  after  the  lapse  of  a  longer  interval  of 
time  the  gradient  here  would  have  become  less  steep, 
just  as  was  the  case  in  the  other  instance  cited. 

The  subsoil  in  which  these  gradients  were  observed 
was  a  fine  sand,  in  some  places  with  grains  so  small 
as  to  approach  the  character  of  quicksand,  and  they 


436  Irrigation  and  Drainage 

represent  conditions  which  are  very  common  in  locali- 
ties where  underdrainage  is  needed,  and,  therefore, 
furnish  a  good  basis  upon  which  to  form  a  judgment 
regarding  the  distance  apart  tile  should  be  laid. 

DEPTH    AT    WHICH    DRAINS     SHOULD    BE    LAID 

The  depth  to  which  water  should  be  lowered  by 
drainage  need  seldom  exceed  4  feet  for  ordinary  farm 
•crops,  and  often  the  lowering  of  the  water  surface 
may  be  less. 

It  should  be  kept  in  mind  that  the  level  of  the 
ground  water  changes  with  the  season,  and  that  many 
lands  benefited  by  underdrainage  are  only  too  wet 
early  in  the  spring,  and  if  such  lands  are  to  be  used 
for  ordinary  farm  crops,  it  may  only  be  needful  to 
draw  the  water  down  so  far  as  to  make  the  surface 
dry  enough  to  give  good  working  conditions  for  the 
soil.  In  such  cases,  tiles  placed  2%  to  3  feet  deep, 
rather  than  3%  to  4  feet,  will  usually  be  found  suffi- 
cient. If  the  tiles  are  placed  deeper  than  this,  not 
only  will  there  be  a  permanent  lowering  of  the  ground 
water,  but  the  low  stage  will  be  reached  so  much 
earlier  in  the  season  that  a  smaller  amount  of  the 
water  flowing  under  the  field  may  be  used  by  the 
crop. 

Where  fields  are  underlaid  by  sandy  subsoils,  it 
is  quite  important  not  to  draw  the  water  down  far 
into  the  sand,  because  the  height  to  which  the  water 
can  be  lifted  rapidly  in  these  by  capillarity  is  quite 
short.  To  carry  the  ground -water  surface  below  this 


Distance   Between   Drains  437 

limit  not  only  lessens  the  amount  of  underflow  which 
becomes  available  to  the  crop,  but  it  also  diminishes 
the  amount  of  the  heavy  summer  rains  which  the 
crop  may  use,  because  when  the  ground  water  is 
carried  too  low  much  of  the  water,  in  times  of  pro- 
longed heavy  rains,  may  pass  below  the  limit  of  root 
feeding  before  the  crop  has  time  to  avail  itself  of  it. 

DISTANCE     BETWEEN     DRAINS 

There  are  three  chief  factors  which  determine  the 
proper  distance  between  underdrains  :  (1)  the  freedom 
with  which  water  may  flow  through  the  subsoil 
toward  the  drains,  (2)  the  depth  at  which  the  drains 
are  placed,  and  (3)  the  interval  of  time  between 
rainfalls  sufficiently  heavy  to  produce  considerable 
percolation. 

It  should  be  clearly  understood  that  it  is  the 
character  of  the  subsoil,  rather  than  that  of  the 
soil,  which  determines  the  rate  at  which  water  moves 
toward  and  into  the  drains,  and  it  should  be  further 
understood  that  the  subsoil  which  takes  part  in  the 
lateral  flow  of  the  water  may  be  several  feet,  even  10 
or  more,  below  the  level  at  which  the  drains  are 
laid. 

If,  for  example,  the  field  to  be  drained  has  a 
rather  close  clay  surface  soil  underlaid  with  two,  three 
or  four  feet  of  heavy  clay,  which  in  turn  is  underlaid 
by  a  stratum  of  sand,  then  the  movement  of  water 
from  the  surface  toward  and  into  the  drains  will 
be  such  as  is  represented  by  the  arrows  in  Fig. 


438  Irrigation  and  Drainage 

136.  That  is,  the  water  moves  along  the  line  of  least 
resistance,  no  matter  how  circuitous  or  how  long  that 
may  be. 

Where  the  cavities  through  which  the  water  must 
flow  are  those  due  to  the  diameter  of   the  soil  grains, 


Fig.  136.    Movements  of  water  toward  tile  drains  where  heavy  clay 
soils  are  underlaid  with  sand. 

the  influence  of  size  of  grain  on  the  rate  of  flow 
is  such  that  the  amount  of  water  passing  a  given 
section  under  otherwise  like  conditions  is  somewhat 
nearly  proportional  to  the  squares  of  the  diameters. 
This  being  true,  if  the  effective  diameter  of  the 
grains  in  the  clay  is  .004  m.m.,  while  that  of  the 
grains  in  the  stratum  of  underlying  sands  is  .07 
m.m.,  then  their  squares  will  be  .0049  and  .000016 
respectively,  in  which  the  ratio  is  nearly  as  300  to 
1,  so  that  the  water  would  flow  through  the  same 
length  and  section  of  sand  about  300  times  as  rapidly 
as  it  would  through  the  clay. 

It  is  also  true  that  the  lengths  of  the  soil  pores 
through  which  water  flows  decrease  the  rate  in  a  ratio 
nearly  proportional  to  the  lengths,  so  that  the  sand 
column  in  the  case  cited,  or,  what  is  the  same  thing, 
the  distance  between  drains,  could  be  300  times  as 
great  as  with  the  clay  and  yet  leave  the  rate  of  flow 
just  as  rapid.  It  is  plain,  therefore,  that  the  move- 


Distance   Between   Drains 


439 


ment  of  the  water  in  cases  like  that  represented  in 
Fig.  136  will  be  chiefly  straight  down  through  the 
soil  and  clay  until  the  sand  is  reached,  when  the 
movement  will  be  sideways  toward  the  drains  and 
finally  upward,  the  water  entering  them  chiefly  from 
the  under  side.  That  is  to  say,  the  flow  sidewise 
through  the  clay  toward  the  drains  will  be  very  slight 
indeed. 

Since  the  resistance  to  flow  of  water  increases  as 
the  soil  texture  becomes  more  close,  it  is  clear  that 
the  more  open  the  soil  the  farther  apart  the  drains 
may  be  placed.  It  is  common  to  place  lines  of  tile 
in  underdraining  varying  distances  apart,  from  30  feet 
to  100  and  even  200  feet.  The  reasons  for  these  wide 
differences  will  be  better  understood  after  considering 
the  way  the  ground -water  surface  changes  under  a 
tile -drained  field  following  a  rain. 


Fig.  137.    The  observed  surface  of  the  ground  water  in  a  tile-drained  field 
48  hours  after  a  rainfall  of  .87  inches. 

In  Fig.  137  is  represented  the  observed  slope  of  the 
ground -water    surface    in    a    tile -drained    field   where 
lines  are   placed  33  feet  apart  and  between  3  and 


440 


Irrigation  and  Drainage 


4  feet  below  the  surface.  The  conditions  there  shown 
had  developed  48  hours  after  a  rainfall  of  .87  inches, 
and  the  facts  were  obtained  by  sinking  lines  of  wells 
at  right  angles  to  the  drains,  there  being  3  wells 
between  each  pair.  It  will  be  seen  that  the  height  of 
the  water  on  the  crest  between  the  drains  varies, 
being  much  greater  at  1  and  2  than  elsewhere,  and 
this  is  where  the  soil  is  more  clayey,  and  so  closer  in 
texture. 

In  Fig.  138  is  represented  the  heights  of  the 
ground -water  surface  midway  between  the  drains  as 
they  occurred  2  days,  2%  days  and  5%  days  after  the 
same  rain,  and  the  differences  in  the  steepness  of  the 
slopes  in  the  several  cases  should  be  understood  as  due 
chiefly  to  differences  in  the  size  of  the  soil  grains.  It 
will  be  seen  that  after  a  period  of  nearly  6  days  the 
surface  of  the  ground  water  in  the  upper  portion  of 


Fig.  138.    Changes  in  the  level  of  the  ground- water  surface  in  tile-drained  field. 

the  field  has  become  quite  flat,  having  fallen  below  the 
level  of  the  drains,  and  the  gradient  being  reduced 
to  1  foot  in  175  feet,  while  at  the  lower  end,  where 
the  soil  is  heavier,  the  slope  is  still  1  in  27. 

Taking  these  two  cases,  let  it  be  assumed  that  it 


Distance   Between   Drains  441 

is  desired  to  place  the  lines  of  tile  close  enough 
together,  so  that  after  6  days  following  an  inch  of 
rain  the  water  shall  nowhere  stand  within  3  feet  of 
the  surface,  and  that  the  tiles  are  placed  4  feet  deep. 
Since  in  the  sandy  subsoil  of  the  upper  part  of  the 


Fig.  139.     Diagram  of  influence  of  distance  between  drains  on 
depth  of  drainage. 

field  the  mean  gradient  is  1  foot  in  175,  the  lines 
of  tile  may,  under  such  conditions,  be  placed  twice 
this  distance  apart,  or  350  feet,  for  then  halfway 
between  them  the  water  would  only  stand  1  foot  above 
the  drains  and  hence  3  feet  below  the  surface.  But 
in  the  lower  part  of  the  field,  where  the  soil  is  finer 
and  where  the  observed  mean  gradient  is  1  in  27, 
the  lines  of  tile  could  only  be  placed  54  feet  apart 
to  ensure  the  same  conditions. 

It  was  pointed  out,  in  connection  with  Fig.  133, 
that  the  slope  of  the  ground  water  toward  the  lake 
was  at  the  rate  of  1  foot  in  24.4  early  in  the  season, 
and  later  1  foot  in  35.86  feet,  which  would  call  for 
placing  the  lines  of  tile  50  to  72  feet  apart.  Refer- 
ring to  the  diagram,  Fig.  139,  it  will  be  readily  under- 
stood that  when  there  is  a  drain  at  A  and  C  only, 
the  soil  undrained  must  be  highest  at  B,  but  if  an 


442  Irrigation  and  Drainage 

intermediate  line  of  tiles  is  placed  at  D,  then  the 
highest  levels  of  the  ground  water  would  be  found  at 
E  and  F,  farther  below  the  surface,  leaving  the  field 
better  drained.  It  is  very  important  that  this  prin- 
ciple be  thoroughly  grasped,  because  so  many  local 
conditions  affect  the  depth  and  distance  apart  at 
which  drains  should  be  placed  that  no  specific  figures 
can  be  safely  followed  in  all  cases.  It  is  generally 
true  that  in  loose,  loamy  soils,  and  especially  if  under- 
laid by  sand,  good  drainage  will  be  secured  with 
drains  100  feet  apart  and  3%  feet  deep.  On  heavier 
soils,  they  must  be  closer,  and  on  more  open  ones 
they  may  be  farther  apart. 

In  regard  to  depths  of  drains,  it  should  be  under- 
stood that  the  deeper  they  are  placed  the  better  work 
they  do  as  a  rule.  If  one  soil  has  had  its  non- 
capillary  pores  -emptied  to  a  depth  of  4  feet,  and 
another  one  only  to  a  depth  of  2  feet,  the  capacity 
of  the  former  to  store  a  heavy  rain  without  over- 
saturation  will  evidently  be  greater  than  that  of  the 
latter,  and  hence  the  shallow  drained  fields  will  oftenest 
become  over -wet  in  wet  seasons.  But  the  cost  of 
digging  4  feet  is  much  greater  than  2%  feet,  the 
expense  increasing  faster  than  in  proportion  to  the 
depth. 

In  cold  climates  the  tiles  must  be  placed  as  deep  as 
2  feet,  to  prevent  their  destruction  by  frost.  Tiles 
are  laid  at  a  depth  of  18  inches,  but  the  practice  is 
not  only  unsafe  so  far  as  destruction  of  the  tiles  is 
concerned,  but  not  half  the  advantage  can  then  be 
secured  which  they  are  capable  of  giving  if  laid  deeper. 


Kinds   of  Drains  443 

KINDS     OP     DRAINS 

Drains  are  called  closed'  or  open,  according  as  they 
are  covered  or  not.  There  are  conditions  under  which 
open  drains  or  ditches  should  and  must  be  used,  but 
the  closed  forms  are  always  to  be  preferred  where 
thorough  drainage  and  facility  in  working  the  land 
are  desired.  In  the  earlier  practice  of  underdraining, 
before  tiles  were  invented  and  manufactured  on  a 
large  scale,  various  means  were  adopted  to  provide 
waterways  through  which  the  water  could  more  readily 
drain  away  from  the  field.  An  early  method  was  to 
place  in  the  bottom  of  a  ditch  bundles  of  faggots  end 
to  end  and  then  fill  in,  expecting  the  water  to  flow 
through  the  spaces  between  the  faggots.  Three 
slender  poles  were  often  used,  one  laid  upon  two 
others,  thus  forming  a  waterway ;  or  again,  a  single 
larger  pole  was  split  in  two  and  these  laid  in  the 
ditch  side  by  side  with  the  flat  faces  up.  Two  boards 
nailed  together  V-shaped  and  laid  on  the  bottom  of 
the  ditch  formed  still  another  method  of  securing 
underground  drains  with  wood. 

Stones  were  also  used  in  various  ways  for  the  same 
purpose ;  sometimes  the  bottom  of  the  ditch  was 
filled  with  small  stones  and  then  covered  ;  two  rows 
of  flat  stones  placed  on  edge  to  form  a  V  opening 
downward,  was  another  common  plan.  Two  flat 
stones  on  edge,  with  a  cover,  were  extensively  used, 
and  some  even  went  to  the  trouble  of  paving  the 
bottom  of  the  ditch  with  flat  stones  and  forming  a 
closed  stone  drain  by  adding  sides  and  top,  which. 


444  Irrigation  and  Drainage 

when  well  done,  was  permanent  and  effective.  Square 
blocks  of  peat  have  been  grooved  on  one  face  and 
two  of  these  placed  together  to  form  a  tile,  thus 
making  a  drain  of  another  kind.  Each  of  these 
methods  of  securing  underdrainage  involved  much 
labor ;  gave  channels  in  which  the  water  flowed  with 
great  resistance ;  clogged  easily,  and  while  beneficial 
results  invariably  followed  their  use,  they  were  neither 
wholly  satisfactory  nor  permanent. 

When  the  manufacture  of  tiles  from  burned  clay 
was  begun,  various  shapes  were  adopted  and  abandoned 
for  the  present  cylindrical  type,  which  when  well 
made  and  laid,  has  been  found  entirely  satisfactory 
for  the  construction  of  closed  drains. 

In  more  recent  years  an  effort  has  been  made  to 
build  a  continuous  line  of  tiles  in  the  bottom  of  the 
ditch  after  it  is  dug  and  graded,  using  a  concrete 
made  from  the  best  hydraulic  cement,  lime  and  sand. 
The  mortar,  when  made,  is  fed  through  a  simple 
machine,  which  determines  the  size  and  shape  of  the 
tile,  making  it  continuous,  cylindrical  and  smooth  on 
the  inside.  A  trowel  is  used  to  cut  the  tile  through 
to  near  the  lower  side  with  sufficient  frequency  to 
permit  the  necessary  percolation  from  the  soil,  thus 
securing  a  drain  with  all  joints  perfect.  The  system, 
however,  has  not  been  sufficiently  long  in  use  to 
enable  one  to  say  how  meritorious  it  is. 

Open  surface  drains,  where  they  are  permanent 
improvements,  should,  if  possible,  be  made  wide  and 
with  sides  so  gently  sloping  as  not  to  be  washed,  and, 
if  possible,  so  as  to  be  grassed  over  and  driven  through 


Kinds   of  Drains  445 

with  mowing  machine,  both  to  keep  it  clean  and  to 
utilize  the  land  for  hay.  In  many  flat  prairie  sec- 
tions there  are  "  runs,"  "draws,"  "sloughs"  or  natural 
waterways,  through  which  the  surface  waters  find 
their  way,  in  the  spring  and  at  times  of  heavy  rains, 
into  drainage  channels.  Such  drainage  must  usually 
be  handled  in  surface  drains,  and  even  when  the 
channel  must  in  places  have  a  depth  of  three  feet, 
it  will  be  cheaper  and  far  better  in  the  long  run  to 
make  them  with  sloping  sides  not  steeper  than  1  in 
2,  or  12  feet  wide  at  the  top.  If  the  work  is  done 
in  the  dry  season,  most  of  it  can  be  accomplished 
with  plow  and  scraper,  and  the  earth  moved  back, 
smoothed  down  and  seeded  to  grass  so  as  to  make 
it  permanent,  easily  cared  for,  and  not  a  serious 
obstruction. 

Where  turns  must  be  made  in  such  drains,  they 
should  have  a  large  curvature  to  prevent  the  water 
cutting  into  the  bank. 

HOW   WATER    ENTERS    TILE    DRAINS 

The  flow  of  water  into  the  tile  drains  takes  place 
through  the  walls  of  the  tiles  and  through  the  joints 
made  by  abutting  the  ends  together.  It  is  a  common 
impression  that  considerable  space  should  be  left 
between  the  ends  of  the  separate  tiles,  in  order  that 
the  water  shall  have  opportunity  to  enter,  and  that  it 
is  quite  necessary  that  the  lengths  of  the  tile  shall  be 
short,  in  order  that  there  shall  be  sufficient  space 
left  for  the  passage  of  the  water. 


446  Irrigation  and  Drainage 

The  facts  are,  however,  that  there  is  so  ready  a 
movement  through  the  walls  of  ordinary,  tiles  them- 
selves, and  through  the  joints  when  they  are  made  as 
perfect  as  possible,  that  every  precaution  should  be 
taken  in  laying  tiles  to  make  perfect  joints,  in  order 
that  the  silt  and  soil  may  be  excluded,  to  prevent 
clogging  the  drain. 

A  series  of  observations  on  2 -inch  Jefferson,  Wis., 
tiles,  relating  to  the  rate  of  percolation  through  the 
pores  in  the  walls,  showed  that  under  a  pressure  of 
23.5  inches  the  discharge  per  100  feet  into  the  tile  was 
at  the  rate  of  8.1  cubic  feet  during  24  hours.  This 
occurred  when  the  walls  were  surrounded  by  water 
only.  When  the  tiles  were  covered  with  a  fine  clay 
loam,  so  that  water  had  to  flow  through  3  inches  of 
this  soil  to  reach  the  tiles,  the  discharge  was  reduced 
to  the  rate  of  1.62  cubic  feet  per  100  feet  of  tile  in 
24  hours.  It  is  plain,  therefore,  that  with  this  poros- 
ity and  with  the  openings  at  the  joints,  there  is 
ample  opportunity  for  the  water  to  find  its  way  into 
the  drains  after  reaching  them,  and  great  pains 
should  always  be  taken  to  make  as  close  joints  as 
possible. 

The  use  of  collars  to  keep  sediment  from  entering 
the  joints  is  not  a  good  practice.  They  will  not,  as 
a  rule,  fit  closely ;  they  tend  to  encourage  careless 
laying;  they  increase  the  first  cost,  and  the  soil,  if 
it  works  under  the  collars  so  as  to  fill  the  space,  will 
retard  the  entrance  of  water  into  the  drain.  Tile  well 
made,  with  ends  square  and  whole,  if  properly  laid, 
make  a  sufficiently  close  joint. 


Gradient   of  Drains  447 

THE  FALL  OR  GRADIENT  FOR  DRAINS 

In  most  cases  where  drainage  is  required,  the  sur- 
face of  the  field  is  so  flat  that  it  is  usually  desirable 
to  secure  as  much  fall  for  the  drains  as  it  is  prac- 
ticable to  get,  and  so  a  careful  study  of  the  field 
should  be  made  with  a  view  to  learning  where  the 
lowest  land  is  and  along  what  line  the  greatest  rate 
of  fall  may  be  secured.  This  is  a  matter  of  the 
greatest  importance,  and  the  less  the  fall  is  the 
greater  should  be  the  attention  given  to  it.  If  a  fall 
of  2  inches  or  more  in  100  feet  can  be  secured,  the 
conditions  are  favorable  for  good  results.  It  often 
happens  that  less  fall  than  this  must  be  accepted,  but 
this  should  be  done  only  after  careful  leveling  has 
proved  a  greater  one  impracticable. 

It  will  frequently  happen  that  the  line  of  lowest 
ground  is  quite  tortuous,  making  the  distance  from  the 
highest  to  the  lowest  point  greater  than  to  follow  a 
straight  Hue.  When  this  is  the  case,  and  the  fall 
very  small,  it  may  often  be  desirable  to  dig  a  little 
deeper  in  places,  cutting  off  bends,  and  thus  increase 
the  fall. 

It  will  generally  be  true,  however,  that  the  main 
drain  should  follow  the  lowest  line  in  order  to  secure 
as  much  fall  for  the  laterals  as  possible,  and  this 
point  is  made  the  more  important  because  the  axis 
of  each  lateral  should  reach  the  main  above  its  center, 
in  order  that  water  in  the  main  shall  not  set  back 
into  it. 

Great  'pains  should  always  be  taken  to  get  a  per- 


448 


Irrigation  and   Drainage 


fectly  uniform  fall  for  the  whole  main  or  the  whole 
of  any  given  lateral,  and  the  greatest  care  should  be 
exercised  to  lay  the  tiles  perfectly  true  to  the  grade 
when  that  has  been  determined.  When  this  is  done, 
there  is  the  least  tendency  for  sediment  to  lodge  and 
clog  the  drain. 

It  will  not  be  possible  in  all  cases  to  maintain  a 
constant  gradient,  and  when  this  is  true  it  is  best 
always  to  change  from  a  less  fall  to  one  which  is 
greater,  because  then  any  sediment  which  should  be 

carried  in  the  upper  part 
of  the  drain  will  also  be 
carried  when  the  fall  is 
increased ;  but  with  the 
reverse  conditions  the 
lower,  fall  must  have  a 
tendency  to  cause  the 
drain  to  become  clogged. 
Where  a  change  from 
a  larger  fall  to  one  less 
must  be  made,  and  the 
latter  gradient  is  3  inches 
per  100  feet  or  less,  it 
will  usually  be  prudent 
to  place  a  silt  basin  where 
the  change  of  grade  oc- 
curs, as  represented  in 
Fig.  140.  The  silt  basin,  if  the  line  of  tiles  is  short 
and  small,  may  be  made  by  sinking  an  8-,  10-  or  12- 
inch  tile  below  the  level  of  the  bottom  of  the  ditch, 
and  then  notching  another  section  of  the  same  size, 


Fig.  140.    Silt  basin. 


Size   of  Tile  449 

so  that  it  may  receive  the  drain  from  above  and  be- 
low. The  sediment  brought  will  then  be  dropped  in 
the  still  water  of  the  basin,  and  may  be  removed  from 
time  to  time.  To  bring  the  silt  basin  to  the  top  of 
the  ground,  it  will  be  best  to  use  one  length  of  the 
glazed  sewer  tile,  because  this  will  not  be  injured  by 
freezing.  Where  the  line  of  tiles  is  large,  and  much 
sediment  is  likely  to  be  moved,  the  silt  basin  should 
be  dug  larger  and  bricked  up.  Silt  basins  should  be 
kept  covered  to  avoid  accidents,  and  especially  in  win- 
ter, to  prevent  injury  to  the  tile  by  freezing. 

SIZE    OF    TILE    TO    USE 

It  is  not  possible  to  give  specific  directions  for 
selecting  the  sizes  of  tiles  which  are  best,  except  where 
all  the  details  regarding  the  field  to  be  drained  are 
known.  It  may  be  said,  in  general,  that  their  capacity 
must  be  large  enough  to  remove  the  excess  of  water 
of  the  heaviest  rains  which  fall  inside  of  24  to  48 
hours,  but  how  much  this  excess  may  be  will  vary 
between  wide  limits. 

If  the  tile  are  3%  to  4  feet  deep,  and  the  soil  has 
been  depleted  of  its  moisture  by  a  heavy  crop,  the 
cases  are  very  exceptional  when  even  a  rainfall 
of  2.5  inches  in  24  hours  would  produce  much  per- 
colation into  the  drains.  It  is  the  rains  in  the 
spring  of  the  year  which  will  most  tax  the  drains, 
but  it  should  be  understood  that  so  long  as  the 
water  is  moving  quite  rapidly  through  the  soil  it  is 
sucking  fresh  air  in  after  it,  and  there  is  little  danger 

oo 


450  Irrigation  and  Drainage 

to  crops,  and  for  this  reason  much,  smaller  tiles  are 
permissible  than  would  otherwise  be  the  case.  It  is 
when  the  ground  water  in  a  cultivated  field  becomes 
stagnant  or  stationary  that  poisonous  principles  are 
developed  and  suffocation  for  lack  of  air  occurs. 

The  greater  the  gradient  or  fall  of  the  line  of 
tiles,  the  greater  will  be  its  capacity  and  the  smaller 
it  may  be  for  a  given  area.  The  area  of  cross- 
section  of  tiles  increases  in  the  ratio  of  the  squares 
of  the  diameters  ;  thus  for  diameters  of  tiles  of  2, 
3,  4,  5,  6,  7,  8  and  9  inches,  the  areas  will  be  4,  9, 
16,  25,  36,  49,  64,  and  81  square  inches,  and  hence, 
when  running  full  with  the  same  velocity,  their 
capacities  would  be  in  the  relations  of  the  second 
series  of  numbers.  The  friction  on  the  walls  of  the 
tiles,  and  the  eddies  which  the  joints  and  other  ine- 
qualities tend  to  set  up,  reduce  the  velocity  in  the 
small  tiles  more  than  they  do  in  the  large  ones, 
hence  doubling  the  diameter  of  tiles  considerably 
more  than  makes  its  capacity  four  times  as  great. 

The  longer  the  line  of  tiles  the  less  it  is  able  to 
discharge  when  running  full,  but  just  how  much  the 
capacity  is  decreased  by  the  length  cannot  be  simply 
or  accurately  stated. 

In  speaking  of  the  proper  size  of  mains,  C.  G. 
Elliott*  states  :  "  For  drains  not  more  than  500  feet 
long,  a  2 -inch  tile  will  drain  two  acres.  Lines  more 
than  500  feet  long  should  not  be  laid  of  2 -inch 
tiles.  A  3 -inch  tile  will  drain  five  acres,  and  should 
not  be  of  greater  length  than  1,000  feet.  A  4-inch 

*  Practical  Farm  Drainage,  p.  57. 


Size   of  Tile  451 

tile  will  drain  12  acres  ;  a  5 -inch,  20;  a  6 -inch,  40  ; 
and  a  7 -inch  tile  60  acres." 

In  the  earlier  practice  of  underdraining  with  cylin- 
drical tiles,  sizes  as  small  as  1%  inches  were  used  for 
the  laterals,  leading  the  water  into  the  mains,  but  the 
general  tendency  has  been  to  abandon  the  smaller 
sizes  and  to  use  nothing  less  than  3  inches  in 
diameter,  even  for  the  laterals.  The  labor  of  making 
the  small  sizes  is  nearly  as  great  as  that  required  for 
those  3  inches  in  diameter,  thus  leaving  the  differ- 
ence in  cost  chiefly  that  of  the  extra  amount  of  stock 
used  in  the  manufacture.  But  the  3 -inch  size  is  so 
much  safer  to  use  than  the  smaller  ones  that  the 
latter  should  generally  be  abandoned.  The  most  seri- 
ous objection  to  the  small  sizes  is  the  great  difficulty 
in  laying  them  so  exactly  to  grade  as  not  to  have 
them  silt  up. 

The  sizes  of  mains  and  sub -mains,  the  sizes  of 
laterals,  the  lengths  of  each  size  used,  and  the  dis- 
tance between  drains,  can  best  be  shown  by  citing  a 
specific  case  where  the  conditions  to  be  met  have 
been  considered  in  making  the  selections  and  adjust- 
ments. The  case  selected  was  laid  out  under  the 
supervision  of  C.  G.  Elliott,  C.  E.,  and  is  an  80-acre 
farm  in  northern  Illinois,  where  the  soil  is  a  deep, 
rich,  black  loam,  approaching  muck  in  its  lowest 
places,  and  underlaid  at  a  depth  of  2.5  feet  with  a 
yellow  clay  subsoil.  The  fall  of  the  main  drains  in 
this  case  is  not  less  than  2  inches  per  100  feet,  and 
that  of  the  laterals  is  more  rather  than  less. 

The  diagram,  Fig.  141,  shows  that  the  least  distance 


452 


Irrigation   and   Drainage 


between  laterals  is  about  150  feet  ;  an  effort  was  not 
made  to  secure  perfect  drainage,  but  rather  so  nearly 
sufficient  for  ordinary  crops,  as  to  make  the  increase 
in  yield  pay  a  fair  return  for  the  money  invested. 


Fig.  141.  Drainage  system  of  80  acres.  Double  lines  represent  mains  ;  single 
lines  are  laterals.  Numbers  give  length  of  drains  and  diameter  of  tile. 
After  C.  G.  Elliott. 

The  double  lines  represent  the  mains  and  sub -mains; 
the  single  lines  are  laterals,  and  the  numbers  of  three 
or  more  figures  express  the  number  of  feet  of  each 
size  used  in  the  line  against  which  they  stand,  while 
the  single  figures  under  these  show  the  inside  diame- 
ter of  the  tiles  used. 

It  will  be  seen  that  the  main  begins  with  1,000 
feet  of  7 -inch  tiles,  carrying  the  water  from  80  acres 
of  flat  land  surrounded  by  comparatively  level  fields  ; 
next  follow  1,200  feet  of  6-inch  tiles,  then  600  feet 
of  5 -inch,  the  line  closing  with  157  feet  of  4 -inch 
tiles  into  which  no  laterals  lead. 


Outlet   of  Drains 


453 


THE    OUTLET    OF    DRAINS 

Great  pains  should  be  taken  to  secure  a  clear  fall 
at  the  outlet  of  a  drain,  placing  it,  if  possible,  where 
it  will  always  be  above  water,  as  represented  at  A. 
Fig.  142,  rather  than  as  at  B.  If  the  outlet  is  beneath 
water,  the  checking  of  the  velocity  of  outflow  will 
cause  sediment  to  be  thrown  down,  and  will  soon  clog 
the  main.  Care  should  also  be  taken  to  so  guard  the 
outlet  from  the  trampling  of  animals  that  they  shall 


Fig.  142.    Proper  and  improper  outlet  of  drains.    A,  proper  outlet ;  B,  improper 
outlet ;  C,  proper  junction  of  lateral  with  main  ;  D,  improper  junction. 

not  break  down  the  earth  about  it ;  and  against  the 
effect  of  winter  frosts  and  surface  rains,  tending  to 
throw  earth  down  over  the  mouth. 

In  cold  climates  it  will  not  do  to  terminate  the 
main  with  the  ordinary  drain  tile,  as  the  action  of  the 
frost  will  soon  crumble  it  down.  A  common  plan  is 
to  make  a  wooden  outlet,  16  feet  long,  out  of  2 -inch 
lumber,  thus  holding  the  tile  back  beneath  the  sur- 
face sufficiently  far  to  be  safe  against  freezing.  A 
much  better  termination  of  the  main,  however,  and 
one  which  will  be  permanent,  is  glazed  sewer  tile, 
using  not  less  than  10  feet  of  it.  Lap -weld  iron  pipes 


454 


Irrigation   and   Drainage 


Fig.  143.  Method  of  connect- 
ing lateral  with  main  drain. 
After  Jnl.  Kiihn. 


are  also  used  for  this  purpose,  but  a  section  or  two  of 
the  cast  iron  sewer  pipe  of  the  size  of  the  main  will 
be  found  better,  because  more  durable. 

Where  the  laterals  are  connected  with  the  mains, 
an  effort  should  be  made  to  introduce  the  branch 
above  the  axis  of  the  main,  and  where  there  is  fall 
enough  to  permit  of  doing  so  the  method  used  exten- 
sively in  Europe 
seems  to  be  the 
best.  This  con- 
sists in  perforating 
the  top  of  the  main 
and  the  bottom  of 
the  end  tile  of  the 
lateral,  placing  the 
two  openings  together,  as  represented  in  Fig.  143,  but 
first  closing  the  ends  of  the  tile  with  a  stone  and  ball 
of  clay.  This  arrangement  allows  the  lateral  to  empty 
itself  completely  into  the  main,  and  prevents  it  from 
becoming  clogged  with  sediment  by  the  setting  back 
of  water  into  it. 

Where  connection  is  made  direct  with  the  side  of 
the  main,  it  should  be  done  by  approaching  at  an 
angle  down  stream,  as  shown  at  C,  Fig.  142,  rather 
than  as  at  D.  This  can  be  done,  even  if  the  lateral 
is  at  right  angles  to  the  main,  by  curving  the  ditch 
gently  for  a  rod  or  more  as  the  place  of  junction  is 
approached.  With  this  mode  of  joining,  the  least 
interference  is  brought  about  when  the  two  currents 
unite  and  there  is  the  least  tendency  to  clog. 


Obstructions    to    Drains 


455 


OBSTRUCTIONS    TO    DRAINS 

In  all  cases  where  water  flows  through  the  drain 
during  any  considerable  portion  of  the  growing  season, 
care  must  be  taken  to  avoid  the  presence  of  trees 


Fig.  144.    Showing  roots  of  European  larch  removed  from  a  6-inch  tile 
drain,  which  they  had  effectually  clogged. 

anywhere  within  three  or  four  rods  of  the  line  of  tile, 
otherwise  the  roots  will  find  their  way  into  the  drain 
through  the  joints,  and  there  branch  out  into  a  com- 


456  Irrigation  and  Drainage 

plete  mat  of  fine  fibers,  which  will  fill  the  whole  drain 
and  by  arresting  the  silt  moving  with  the  water,  com- 
pletely closes  it.  In  Fig.  144  are  shown  two  bundles 
of  roots  of  the  European  larch  which  entered  and 
completely  choked  a  6 -inch  main  lying  5  feet  below 
the  surface,  and  where  the  trees  were  standing  15  feet 
away,  from  the  line.  There  are  but  few  trees  that 
will  grow  in  such  places  which  can  be  trusted  near 
the  drain,  but  the  willow,  elm,  larch  or  tamarack,  and 
soft  maple  are  among  the  worst.  It  should  be  under- 
stood that  so  long  as  the  water  in  the  drain  is  flowing 
it  is  highly  charged  with  air,  and  trees  may  even  bet- 
ter immerse  their  roots  in  this  than  in  the  more 
stationary  water  between  the  soil  grains,  hence  they 
do  so  wherever  opportunity  is  offered,  unless  the  water 
should  be  poisonous. 

LAYING    OUT    SYSTEMS    OF    DRAINS 

In  preparing  to  drain  a  piece  of  ground  of  con- 
siderable extent,  careful  study  should  always  be  given 
to  the  best  way  of  laying  out  the  system  so  as  to 
secure  the  greatest  fall  and  the  most  complete  drain- 
age with  the  least  digging  and  the  smallest  number 
of  feet  of  tile  at  the  lowest  cost.  To  do  this,  care 
must  be  taken  to  avoid  laying  the  lines  so  as  to 
bring  their  influence  within  territory  already  sufficiently 
drained  by  another  line ;  to  make  the  outlets  and 
junctions  as  few  as  possible  ;  to  avoid  the  necessity 
of  the  more  expensive  large  sizes  of  tiles,  and  of  dig- 
ging more  deeply  than  is  required  for  good  drainage. 


Systems   of  Drains . 


457 


In  Fig.  145  are  represented  diagrammatically  two 
ways  of  laying  out  a  system  of  drains  for  the  same 
piece  of  land.  The  area  drained  is  about  14  acres, 
and  with  lines  of  tile  laid  100  feet  apart,  system 
A  requires  625  feet  of  4 -inch  and  3,020  of  3 -inch 
tiles,  while  that  of  B  makes  necessary  only  550  feet 


Fig.  145.    Two  systems  of  laying  out  drains. 

of   4 -inch    and    2,830    feet    of    3 -inch   tiles   to   drain 
equally  well  the  same  area. 

Where  long  lines  of  tile  must  be  laid  in  which 
more  than  one  size  will  be  required,  three  systems 
have  been  adopted,  that  represented  in  A,  Fig.  145, 
already  described ;  a  second,  A,  Fig.  146,  and  a  third, 
B,  in  the  same  figure.  In  the  case  of  A,  Fig.  146, 
covering  a  section  2,000  feet  by  900  feet  above  the 


458 


Irrigation  and  Drainage 


s"  s"  s" 


3'  3"  3 ' 


3*  3"  3* 


"3"  3" 


line  a  a,  there  would  be  required  9,000  feet  of  3 -inch 
tiles  and  9,000  feet  of  4-inch  tiles,  with  lines  laid 
100  feet  apart ;  but  following  the  second  system,  B, 

it  would  only  be  neces- 
sary to  lay  3,000  feet  of 
4-inch  tiles,  with  15,300 
feet  of  3 -inch.  At  1 
cent  per  foot  for  3 -inch 
and  1.6  cents  for  4 -inch 
tile,  the  difference  be- 
tween the  purchase  price 
of  the  two  sets  of  tile 
would  be  $33  in  favor 
of  the  system  B.  The 
saving  grows  out  of  the 
fact  that  one  line  of  4- 
inch  tile  has  ample  ca- 
pacity to  drain  not  only 

Fig.  146.    Two  systems  of  laying  out  drains.    ^     strjp     Qf     ground    it 

traverses,  but  at  the  same  time  to  discharge  the  water 
gathered  by  the  three  lines  of  3 -inch  tile  emptying 
into  it  from  the  upper  half  of  the  field. 

It  will  be  observed  that  in  both  diagrams  the  nine 
lines  of  tile  have  been  brought  to  one  outlet  in  the 
stream,  rather  than  to  make  them  all  separate,  as 
might  be  done  in  A,  or  to  make  three  outlets,  as  could 
readily  have  been  done  in  the  case  of  B.  To  have 
finished  the  system  with  three  outlets  would  not  have 
been  a  bad  or  expensive  plan,  but  to  have  as  many 
outlets  as  there  are  lines  of  tile  is  not  generally  to 
be  recommended. 


Intercepting    Underflow  459 

In  actual  practice,  it  will  usually  be  found  that  no 
single  system,  such  as  has  been  represented,  can  be 
used  alone,  but  rather  a  combination  of  them  in 
various  ways  growing  out  of  the  irregularity  of  slopes 
and  surface  conditions. 


INTERCEPTING    THE    UNDERFLOW    FROM    HILLSIDES 

Cases  are  not  infrequent  where  seepage  from  the 
high  lands  surrounding  a  flat  area  approaches  so  close 
to  the  surface  afc  the  foot  of  the  rising  ground  that  a 
single  line  of  underdrains  placed  here  at  a  good 


Fig.  147.     Structural  conditions  producing  swamp  lands  by  underflow,  and 
methods  of  intercepting  the  underflow. 

depth  will  so  completely  intercept  the  underflow  as  to 
make  little  other  draining  needed.  The  structural 
conditions  which  render  underdrainage  in  such  cases 
needful,  the  method  of  accomplishing  it,  and  the 
underlying  principle,  are  represented  in  Fig.  147. 

In    this    case    the    comparatively   impervious    rock 
bottom   of   the  valley  holds   up   the  water   and  forces 


460  Irrigation   and   Drainage 

it  to  spread  laterally  and  to  underflow  the  low  ground 
through  the  sandy  stratum  covered  by  the  closer 
textured  layer  above,  and  to  rise  up  through  that 
s0il  layer,  both  by  hydrostatic  pressure  and  by  cap- 
illarity, and  thus  keep  it  too  wet  for  agricultural 
purposes.  But  when  tiles  are  placed  at  A  and  B, 
at  the  foot  of  the  high  lands  on  both  sides,  the  water 
can  more  easily  escape  into  the  drain  than  it  can  flow 
on  through  the  sand  stratum,  and  the  result  is,  the 
pressure  which  before  was  forcing  the  water  beyond 
A  to  the  left  and  beyond  B  to  the  right  may  now  be 
so  nearly  all  absorbed  by  the  flow  of  water  into  the 
tile  drains  that  no  more  water  reaches  the  flat  land 
between  them  than  is  needed  to  meet  the  demands  of 
vegetation  and  surface  evaporation^  The  case  is 
exactly  similar  to  what  is  shown  in  the  lower  portion 
of  the  diagram ;  here  it  is  plain  that  if  water  is 
allowed  to  discharge  at  C  and  D  nearly  as  fast  as  the 
pipes  can  bring  it  from  the  reservoir,  there  would 
be  little  left  to  pass  on  and  escape  through  openings 
beyond,  while  if  C  and  D  are  closed,  the  full  pressure 
would  operate  to  increase  the  discharge  at  lower 
openings,  as  at  E. 

DRAINING     SINKS    AND     PONDS 

It  frequently  occurs  that  low  places  are  entirely 
surrounded  by  such  high  lands  as  to  make  it  difficult 
to  provide  an  outlet  for  the  surface  water  which  col- 
lects in  them,  especially  during  the  winter  and  early 
spring,  keeping  them  too  wet  for  agricultural  purposes. 


Draining    Sinks   and   Ponds 


461 


Where  the  water  collecting  in  such  places  is 
largely  from  surface  drainage,  it  is  frequently  possible 
to  reclaim  them  by  intercepting  the  water  and  divert- 
ing it  around  the  sink  in  the  manner  suggested  in 
Fig.  148,  where  A  B 
represents  a  surface 
ditch  taking  the  water 
from  the  higher  land 
above. 

It  is  frequently  true 
that  such  low  places 
without  natural  outlets 
are  underlaid  with  well 
drained  beds  of  coarse 
sand  and  gravel,  and 
in  such  cases,  if  the 
volume  of  water  is  not 

Very    large    and    if    the      Fig- 

.,      . 

bed  ot  sand  and  gravel 
beneath  it  is  thick  and  only  10  to  15  feet  from  the 
surface,  a  well  sunk  into  the  sand  and  gravel  and 
stoned  or  bricked  up  may  serve  as  an  outlet  for  under 
or  surface  drains. 

Instead  of  curbing  the  well,  it  may  be  simply  filled 
with  loose  stones  to  within  3  feet  of  the  surface, 
covering  these  with  smaller  ones  and  finally  with 
gravel  and  then  sand,  leaving  the  surface  unobstructed. 

Unless  the  approach  to  this  drain  is  so  gradual 
that  there  is  no  danger  of  fine  silt  being  deposited  over 
it,  it  would  be  better  to  have  this  in  a  shallow  sink 
surrounded  by  a  slightly  higher  border,  grassed  over 


Metnod  of  intercepting  surface  drain- 
age.    A,  B,  surface  ditch. 


462 


Irrigation   and   Drainage 


to  hold  back  the  water  and  throw  down  the  sediment 
before  reaching  this  place,  as  shown  in  Fig.  149, 
where  a  pit  has  been  sunk  into  the  porous  gravel 
below  and  broadened  at  the  surface  to  give  more  area 
for  percolation  through  the  finer  material  at  the  top. 
There  are  also  represented  lines  of  underdrains  leading 
to  the  filter  outlet,  which  might  be  needed  in  order  to 
bring  the  land  quickly  into  the  best  condition.  If 
necessary,  a  line  of  such  wells  may  be  formed  in  a 
surface  ditch  or  depression,  and  thus  increase  the 
capacity. 

THE  USE  OF  TREES  IN  DRAINAGE 

In  some  instances  where  sinks  without  available 
outlets  are  to  be  drained,  and  where  the  method 
illustrated  in  Fig.  149  cannot  be  used,  it  is  pos- 


Fig.  149.    Method  of  draining  sinks. 

sible  to  throw  up  lands  of  higher  ground  with  deep, 
open  ditches  between  them,  in  the  lowest  portion  of 
the  sink,  into  which  the  other  ground  may  be  drained, 
and  then  plant  water -loving  trees,  like  the  willow  or 
larch,  on  the  sides  of  the  ditches,  where,  by  their 


Draining   Sinks   and   Ponds 


463 


rapid  growth  and  large  evaporation  of  moisture 
through  the  foliage,  considerable  amounts  of  water 
will  be  removed.  The  most  serious  objection  to  the 
method  is  the  fact  that  the  trees  will  not  render  their 
greatest  service  early  in  the  season,  and  may  not  fit 
the  ground  for  early  crops  other  than  grass. 


THE    USE    OF    THE    WINDMILL    IN    DRAINAGE 

In  such  places  as  those  under  consideration  in  the 
last  two  sections,  a  good  windmill  may  be  made  to 
drain  a  considerable  area  of  ground  where  only  the 


Fig.  150.    Method  of  draining  sinks  by  wind  power. 

underflow  must  be  handled,  and  where  the  lift  need 
not  be  more  than  20  feet. 

If  the  water  is  to  be  raised  to  a  level  at  which 
gravity  will  remove  it,  then  a  sump  or  reservoir 
should  be  sunk  in  the  ground  as  near  the  place  where 
the  water  is  to  be  disposed  of  as  practicable,  deep 
enough  to  hold  the  drainage  of  two  or  three  days 
when,  for  lack  of  wind,  the  mill  may  be  idle. 

In  order  that  the  mill  may  work  during  the  winter 
also  in  cold  climates,  the  pump  may  be  placed  in  a 


464  Irrigation   and   Drainage 

well,  as  in  Fig.  150,  into  which  the  main  drain,  A, 
discharges,  and  from  which  there  is  an  overflow,  B, 
to  the  reservoir.  The  object  of  the  well  is  to  place 
the  pump  under  conditions  where  it  will  not  freeze  in 
the  severest  weather,  and  thus  prevent  the  ground  from 
becoming  over- saturated  at  any  season1.  The  water  may 
be  made  to  discharge  through  an  under -ground  drain 
connected  directly  with  the  pump,  as  at  C,  or  a  flume- 
box  above  ground  may  be  used,  as  is  most  convenient. 

It  might  even  be  practicable  to  have  this  drainage 
water  discharged  into  a  reservoir  and  used  for  irriga- 
tion at  a  lower  level  during  the  dry  season  of  the 
year,  or  it  would  be  practicable  to  discharge  it  into  a 
series  of  tiles  laid  2  feet  below  the  surface  on  a 
section  of  higher  ground  which  is  naturally  well 
drained,  and  thus  sub -irrigate  this  at  the  same  time 
the  low  place  is  being  drained,  the  two  systems  caring 
for  themselves  continuously. 

LANDS    WHICH    MUST    BE    SURFACE    DRAINED 

There  are  many  ancient  lake  bottoms  now  consti- 
tuting wide  stretches  of  very  flat  country  underlaid  by 
heavy  deposits  of  a  very  close  lacustrian  clay,  through 
which  water  percolates  with  extreme  slowness.  Such 
lands  must  generally  be  surface  drained,  not  only 
because  it  is  difficult  to  find  adequate  fall  for  proper 
outlets  for  underdrains,  but  because  the  water  would 
not  reach  underdrains  quickly  enough  to  meet  the 
demands  of  crops  unless  the  lines  were  laid  closer 
together  than  could  be  afforded. 


Surface   Drainage  465 

Even  through  a  clay  loam*  it  may  require  24  hours 
for  1.6  inches  of  water  to  percolate  through  a  stratum 
of  soil  14  inches  deep  when  the  surface  is  kept  under 
2  inches  of  water,  and  since  the  rate  of  percolation  is 
somewhat  nearly  proportional  to  the  length  of  the 
column,  2  days  would  be  required  for  the  same  flow 
through  28  inches,  and  about  13  days  through  15  feet, 
the  distance  the  water  would  have  to  travel  with 
underdrains  placed  only  30  feet  apart.  But  the  sub- 
soils of  the  lands  in  question  are  much  closer  than 
the  loam  cited,  so  that  the  best  which  has  yet  been 
done  for  such  soils  is  to  plow  them  in  narrow  lands, 
with  the  dead  furrows  extending  along  the  slope  of 
the  fields  in  such  a  way  that  the  excess  of  water  may 
be  quickly  led  away  into  the  streams  or  open  ditches. 

It  is  true  that  the  tillage  and  heavy  cropping  of 
such  soils,  especially  during  dry  seasons,  tend  to  cause 
the  clay  subsoils  to  shrink  into  cuboidal  blocks,  and 
thus  facilitate  underdrainage ;  but  the  long  years 
which  some  of  those  lands  have  been  under  such 
treatment  without  marked  amelioration  appear  to 
leave  little  hope  of  ever  bringing  them  under  thorough 
drainage  in  this  way. 

There  are  other  flat  sections  of  country,  with  more 
open  soils  and  subsoils,  where  sufficiently  deep  open 
ditches  may  be  provided  to  serve  as  outlets  for  under- 
drains, and  lands  be  thus  thoroughly  reclaimed.  Such  is 
the  case  in  Illinois,  and  Fig.  151  represents  six  square 
miles  of  land  treated  in  this  way.  In  this  figure  the 
double  lines  represent  deep  open  ditches,  the  single  lines 

*The  Soil,  p.  171. 
DD 


466 


Irrigation   and   Drainage 


underdrains,   and   the    small    squares    cover   40    acres 

each. 

Another  drainage  system  of  this  sort  in  the  same 
state  "is  found  in  Mason  and  Tazewell  counties,  where 
by  a  cooperative  plan  the  open  ditches  have  been  dug 


Fig.  151.  Plan  of  drainage  of  lands  of  the  Illinois  Agricultural  Company, 
Rontoul,  Illinois.  After  J.  O.  Baker.  The  smallest  squares  are  40 
acres ;  douhle  lines  show  open  ditches;  single  lines  are  tile  drains. 

and  the  expense  divided  among  the  landowners  in 
proportion  to  the  benefits  derived.  The  work  was 
begun  in  1883,  completed  in  1886,  and  has  17.5  miles 
of  main  ditch  30  to  60  feet  wide  at  the  top  and  8  to  11 
feet  deep.  Leading  into  these  mains  there  are  five 
laterals  30  feet  wide  at  the  top  and  from  7  to  9  feet 
deep,  the  whole  system  embracing  70  miles  of  open 
ditch,  excavated  for  the  express  purpose  of  providing 
outlets  for  underdrains  after  the  manner  of  Fig.  151. 


CHAPTER  XIII 

PRACTICAL  DETAILS   OF   UNDERDRAWING 

To  do  the  best  work  in  underdraining  requires  not 
only  a  thorough  knowledge  of  the  principles,  but  an 
extended  practical  experience  in  laying  out  systems  of 
drains.  The  man  who  has  a  thorough  grasfc  of  this 
business,  and  is  experienced  in  laying  out  work  and 
in  the  use  of  precise  instruments  for  leveling  and 
establishing  grades,  can,  with  the  aid  of  eye  and 
instruments,  determine  rapidly  and  accurately  in  the 
field  the  best  place  for  the  mains  and  sub -mains  with- 
out making  a  detailed  survey ;  and  where  large  areas 
are  to  be  drained,  especially  if  the  fall  must  be  small, 
it  will  usually  be  safer,  better  and  cheaper  to  employ 
some  man  of  experience  who  can  be  trusted  to  do  the 
work  of  leveling,  determining  grades  and  accurately 
staking  out  ready  for  the  ditcher  both  mains  and  lat- 
erals. 

Indeed,  if  a  considerable  amount  of  work  is  to  be 
done,  it  will  in  most  cases  be  better  and  cheaper  in 
the  end  to  entrust  the  whole  job  to  a  man  who  makes 
underdraining  his  business,  and  who  employs  and 
superintends  his  own  crew  of  trained  men.  The  mat- 
ter of  ditching,  even,  is  so  much  of  an  art  that  both 
intelligence  and  experience  are  required  to  do  it  well. 

(467) 


468  Irrigation   and   Drainage 

So  true  is  this,  that  a  good  drainage  engineer  employs 
his  men  by  the  season  or  longer,  if  possible,  and 
divides  his  work  among  them  in  such  a  way  that  each 
man  does  only  one  kind  of  digging.  In  this  way  each 
one  becomes  an  expert  in  his  place,  doing  more  and 
better  work  with  less  effort  than  is  possible  in  any 
other  way.  The  man  who  finishes  the  bottom  of  the 
ditch  and  the  man  who  lays  the  tiles  must  not  only 
be  skillful,  but  must  be  thoroughly  trustworthy  and 
patient,  or  faulty  work  will  be  done.  The  work 
is  often  so  unpleasant,  defects  are  so  easily  covered 
from  inspection,  and  it  will  be  so  long  before  they 
could  be  discovered  and  the  responsibility  properly 
placed,  that  only  men  of  peculiar  fitness  should  ever 
be  trusted  with  it.  These  men  must  be  well  paid, 
they  must  not  be  crowded,  and  there  must  be  nothing 
else  to  take  their  attention.  When  the  right  sort  of 
man  has  been  secured  for  this  work,  and  has  been 
trained  to  it,  he  is  far  more  to  be  trusted  than  almost 
any  farmer,  even  for  whom  the  work  is  to  be  done, 
because  the  farmer  will  have  so  many  other  things  to 
take  his  attention,  and  he  will  be  so  anxious  to  have 
the  job  off  his  hands,  that  his  patience  will  not  per- 
mit him  to  take  the  necessary  time  to  get  every  joint 
of  the  100,000  just  right  before  it  is  left.  Important 
drainage  work,  then,  should  be  left  to  expert  men 
wherever  practicable. 

It  is  very  important  that  the  farmer  who  has  land 
to  drain  should  thoroughly  appreciate  these  essential 
conditions  for  safe  work,  not  only  to  prevent  himself 
from  undertaking  what  he  cannot  hope  himself  to  do 


Drainage   Levels 


469 


well,  but,  what  is  more  important,  that  he  may  be 
able  to  recognize  the  essential  qualities  in  the  man 
who  will  place  the  tiles,  and  satisfy  himself  that  he 
possesses  them. 

It  will  often  happen,  however,  that  drainage 
experts  cannot  be  had,  and  there  may  be  small  areas 
to  drain,  involving  relatively  but  small  expense, 
where  the  farmer  may  do  his  own  work  or  super- 
vise it. 

METHODS    OF    DETERMINING    LEVELS 

Where  the  services  of  a  man  with  instruments  for 
determining  levels  for  lines  of  drains  cannot  be  had, 
there  are  various  simple  means  for  doing  this  work 
which  may  be  employed  „  n 

where  great  accuracy  is  not    !  ^ ^^ A 

required,  and  among  these  ^-<- 
perhaps  the  safest  is  the  water-level, 
represented  in  Fig.  152.  This  may 
be  made  of  %-inch  gas  pipe,  with  two 
elbows  and  a  T,  as  shown  in  the  sketch, 
the  standard  being  sharpened  by  a  black- 
smith or  by  inserting  a  wooden  point. 
In  the  two  elbows,  which  are  about 
four  feet  apart,  there  are  cemented 
short  pieces  of  glass  tube,  or  slender 
phials,  %-inch  in  diameter,  with  the 
bottoms  broken  out,  and  provided  with  corks.  To  use 
the  instrument,  the  tube  is  filled  with  water  colored  with 
bluing  or  ink,  so  as  to  show  in  the  two  tubes  of 
glass,  when  the  arm  is  horizontal.  By  forcing  the  foot 


Fig.  152. 
Construction 

of  a 
water-level. 


470 


Irrigation   and   Drainage 


of  the  instrument  into  the  ground  until  it  stands  firmly, 
and  removing  the  corks,  the  water  will  come  to  a  level 
at  once,  so  that  if  the  operator  stands  back  about 
four  feet  he  may  sight  across  the  two  surfaces  to 
determine  differences  of  level.  If  one  uses  this  instru- 


Fig.  153.    Four  forms  of  drainage  levels,  with  target-rods. 

ment   with  care,  avoiding  too  long  ranges,  good  work 
may  be  done  with  it. 

A  carpenter's  level  is  sometimes  mounted  in  a 
similar  manner  and  used,  but  it  is  not  as  safe  a 
device,  because  the  level  itself  is  liable  to  be  in  error 


Use   of  Drainage   Levels  471 

and  there  will  be  errors  in  deciding  when  it  is  set 
exactly,  whereas  the  water-level  can  never  be  in  error, 
and  automatically  adjusts  itself  at  once,  the  only 
chances  for  error  being  in  taking  the  sights.  Other 
forms  of  drainage  levels  are  represented  in  Fig.  153, 


LEVELING    A    FIELD 

If  the  field  has  but  small  fall,  and  is  quite  flat  and 
even,  so  that  the  inexperienced  eye  fails  to  detect  the 
direction  of  greatest  slope,  it  will  usually  be  safest  to 
check  it  into  squares  of  50  or  100  feet,  driving  short 
stakes  at  the  several  corners,  whose  elevations  may 
then  be  determined.  To  do  the  leveling,  set  the 
instrument  at  a,  Fig.  155,  midway  between  stations 
1-1  and  1-2,  having  first  provided  a  notebook,  ruled 
as  indicated  in  the  table  below.  Turning  the  level 
first  upon  1-1,  its  distance  below  the  instrument  is 
read  on  the  target -rod  held  upon  that  stake,  and 
the  result,  4  feet,  is  recorded  in  the  table  in  the 
column  headed  "back-sight."  The  instrument  is  next 
directed  to  1-2  and  its  distance  below  the  level  found 
to  be  3.8  feet,  which  shows  that  its  elevation  must  be 

4  ft.— 3.8  ft.=.2  ft. 

above  that  of  station  1-1.  This  reading  of  the  target- 
rod  is  entered  in  the  column  headed  "fore -sight."  In 
the  column  headed  "  Elevation "  the  first  station  is 
given  arbitrarily  a  value  of  10  feet,  as  is  customary 
to  avoid  minus  signs,  and  on  the  same  plan  station 


472  Irrigation  and  Drainage 

1-2  will   have    an   elevation  of  10.2  feet,  as  stated  in 
the  table. 

Table  giving  data  obtained  in  leveling  field,  Fig.  156 

Station  Back-sight           Fore-sight  Difference  Elevation 

1-1  4  10 

1-2  4.2  3.8  .2  10.2 

1-3  3.8  4  .2  10.4 

1-4  4  3.6  .2  10.6 

1-5  3.9  3.8  .2  10.8 

1-6  4  3.7  .2  11 

II-6  3.8  3.98  .02  11.02 

11-5  3.9  3.995  .195  10.825 

II-4  4  4.095  .195  10.63 

II-3  4.1  4.19  .19  10.44 

II-2  3.9  4.26  .16  10.28 

II-l  3.8  3.98  .08  10.2 

III-l  4  3.6  .2  10.4 

III-2  3.9  3.96  .04  10.44 

111-3  4.2  3.775  .125  10.565 

III-4  4.1  4.045  .155  10.72 

III-5  3.8  3.93  .17  10.89 

III-6  4.1  3.625  .185  11.075 

IV-6  4  4.185  .085  11.16 

1V-5  3.84  .16  11 

The  level  is  now  moved  to  b  and  the  distance  of 
[-2  below  it  again  measured  and  found  to  be  4.2  feet, 
which  is  entered  in  the  notebook  under  "  back-sight," 
and  the  instrument  turned  upon  1-3,  where  the  read- 
ing is  found  to  be  4  feet,  and  entered  in  the  table. 
The  difference  between  the  fore-  and  back-sights, 
placed  in  the  column  headed  "  Difference,"  shows  how 
much  higher  one  station  is  than  another,  and  when 
the  first  is  added  to  the  elevation  above  datum,  10 


Use   of  Drainage   Levels  473 

feet,  at  station  1-1,  it  gives  10.2  feet,  or  the 
elevation  of  station  1-2  above  the  same  plane.  The 
difference,  .2  feet,  between  stations  1-2  and  1-3  added 
to  the  elevation  of  1-2,  gives  10.4  feet,  or  that  of 
station  1-3.  In  this  manner  the  instrument  is  moved 
forward  step  by  step  until  measurements  from  e  have 
been  made,  when  the  level  is  next  set  at  /,  and  back- 
and  fore -sights  taken  and  entered,  as  shown  in  the 
table,  so  as  to  connect  the  observations  of  the  first 
line  with  those  of  the  second  line  of  stations. 

Proceeding  to  g,  the  steps  described  are  repeated 
by  moving  back  through  k,  i,  j,  k  and  I  to  m,  and  so 
on  until  the  elevations  of  all  the  stations  have  been 
determined  and  entered  in  the  table.  It  will  be 


l^Z^-:-^^^^f&gtt&** 

^^!^&-M ^3J§$B  £:?:£**&* 


Fig.  154.    Method  of  leveling. 

observed  that  when  proceeding  from  higher  to  lower 
levels  it  is  necessary  to  subtract  the  value  in  the 
column  of  differences  from  the  elevation  of  the  station 
preceding  it,  in  order  to  obtain  the  elevation  of  the 
station  for  that  difference. 

In  Fig.  154  is  shown  the  method  of  leveling 
described  where  the  different  positions  of  the  level 
and  of  the  target  along  one  line  are  shown  in  ele- 
vation. 


474 


Irrigation   and   Drainage 


LOCATION     OF    MAIN     DRAINS    AND     LATERALS 

After  the  notes  of  the  field  leveling  have  been 
obtained,  and  the  elevations  computed  from  them, 
these  may  be  transferred  to  a  diagram  of  the  field,  as 


VI 


IV 


III 


II 


Fig.  155.    Leveling  for  a  contour  map  of  field  to  be  drained. 

in  Fig.  155,  where  they  will  show  at  a  glance  the 
slope  of  the  surface,  and  where  the  mains  must  be 
placed  in  order  to  secure  the  greatest  fall,  both  for 
them  and  for  the  laterals.  It  will  be  seen  that  station 
VI -6  is  the  highest  point  in  the  field,  while  1-1  is  the 


Location   of  Mains   and   Laterals 


475 


lowest,  and  that  if  a  straight  main  were  laid  through 
these  two  points  it  would  be  given  the  course  along 
which  surface  water  would  naturally  flow,  which  is 
also  the  direction  of  steepest  slope. 

The   dotted    lines    in    the    figure    are   contours,  or 


Fig.  156.    Arranging  drains  to  secure  the  maximum  fall. 

lines  of  equal  elevation,  and  as  in  this  case  these 
are  circumferences  of  circles  with  centers  at  station 
1-1,  it  is  clear  that  the  shortest  distance  between  any 
two  contours  will  be  measured  along  their  radii,  and 
hence,  that  there  also  will  be  the  greatest  fall.  Since 
the  diagonal  line  from  VI- 6  and ,  the  lines  I  and  1 


476  Irrigation  and  Drainage 

are  each  a  radius  of  a  circle  from  the  same  center, 
1-1,  the  fall  along  each  will  be  the  same,  namely,  2.4 
inches  per  100  feet ;  hence,  to  drain  this  piece  of 
land,  three  mains  may  occupy  the  positions  of  these 
three  lines,  meeting  at  station  1-1.  But  if  laterals 
are  to  be  placed  100  feet  apart,  these  could  be  given 
about  as  great  a  fall  if  they  were  to  connect  with  the 
diagonal  as  a  main,  and  take  the  positions  indicated 
by  the  two  right -angle  systems  of  lines  in  Fig,  155, 
I,  II,  III,  IV,  V,  representing  laterals  on  the  upper 
side  of  the  main,  and  1,  2,  3,  4,  5  on  the  lower.  If, 
however,  drains  were  to  be  placed  50  feet  apart,  then 
the  most  rapid  fall  could  be  secured  and  the  least 
amount  of  tile  would  be  required,  by  arranging  the 
laterals  as  shown  in  Fig.  156,  where  the  same  area 
is  represented  with  the  contour  lines  drawn  100  feet 
apart  horizontally  and  .2  foot  vertically,  as  they  are 
also  in  Fig.  155,  and  where  the  heavy  ruling  repre- 
sents main  drains  and  the  light  ones  laterals. 

STAKING    OUT    DRAINS 

When  the  location  of  mains  and  laterals  has  been 
determined,  the  next  step  in  the  practical  work  is 
staking  out  the  drains.  There  are  various  methods  of 
doing  this,  but  one  of  the  best  is  as  follows  :  Short 
stakes,  about  8  to  10  inches  long,  called  grade  pegs, 
are  provided,  and  another  set  upon  which  records  can 
be  made  with  lead  pencil,  longer  than  the  others,  and 
called  finders.  With  a  tape  line  or  chain  and  hatchet, 
the  work  begins  by  laying  off  along  the  main,  begin- 


Laying    Chit   Drains  477 

ning  at  the  outlet,  intervals  of  50  feet,  at  each  of 
which  a  grade  peg  is  set  about  12  inches  to  one  side 
of  the  center  of  the  ditch,  where  they  will  not  be 
disturbed,  driving  them  down  flush  with  the  surface 
of  the  ground.  About  6  inches  farther  back  from 
the  line  of  the  ditch  a  finder  is  also  set.  Sub -mains 
and  laterals  are  staked  off  in  a  similar  manner,  and 
when  this  is  done  the  work  of  leveling  for  digging 
the  ditches  may  begin. 

DETERMINING     THE    GRADE   AND    DEPTH     OP 
THE   DITCHES 

The  determination  of  the  levels  of  the  grade  pegs 
should  begin  at  the  outlet  of  the  main,  and  proceed  in 
the  manner  already  described  in  leveling  the  field,  enter- 
ing the  figures  in  a  table  prepared  in  the  notebook, 
as  shown  below : 

Table  shoiving  field  notes  for  determining  depth  of  ditch  and  grade  of  drain 

Depth  of 


Station 

Back-sight 

Fore-sight 

Difference 

Elevations 

Grade  line 

ditch 

Outlet 

7 

.... 

.  .  . 

7 

7 

0 

0 

4 

3 

10 

7 

3 

50 

3.97 

3.87 

.13 

10.13 

7.12 

3.01 

100 

4.2 

3.83 

.14 

10.27 

7.24 

3.03 

150 

4.1 

4.08 

.12 

10.39 

7.36 

3.03 

200 

3.95 

3.99 

.11 

10.5 

7.48 

3.02 

250 

3.87 

3.82 

.13 

10.63 

7.6 

3.03 

300 

4 

3.69 

.18 

10.81 

7.72 

3.09 

350 

4.25 

3.83 

.17 

10.98 

7.84 

3.14 

400 

4.08 

4.1 

.15 

11.13 

7.96 

3.17 

450 

4.05 

3.96 

.12 

11.25 

8.08 

3.17 

500 

3.97 

3.95 

.1 

11.35 

8.2 

3.15 

550 

3.75 

3.97 

11.35 

8.02 

3.03 

600 

3.74 

.01 

11.36 

8.44 

2.92 

478 


Irrigation   and  Drainage 


Referring  to  157,  which  is  a  profile  of  the  data  in 
the  table,  A  is  the  outlet  of  the  drain ;  the  first  stake 
set  is  marked  0,  the  second  50,  etc.,  up  to  600,  the 
numbers  expressing  the  number  of  feet  from  the  out- 
let. The  datum  plane  is  chosen  10  feet  below  the 


50       100     150 


350      400       450       500        550      600 


~J-  ~         7         7.12'.     7.24'-- 7.3ii'     7.18'  "'7. 60 '    7.72'    7.84'     7.3fi-  S.OJJ'     8.20 '    8.32'' "  S.-u' 

-'^ 

^^^^^"^^^M^^^^^^W^^^^  V    ^A^ 


Fig.  157.    Determining  grade  line  and  depth  of  ditch. 

surface  of  the  ground,  at  station  0,  and  the  ground 
here  is  3  feet  above  the  bottom  of  the  drain,  which 
leaves  the  outlet  7  feet  above  datum,  as  stated  in  the 
table,  which  is  also  the  elevation  of  the  grade  line  at 
this  place. 

Referring  to  the  table,  in  the  column  of  elevations 
it  will  be  seen  that  the  surface  of  the  ground  .at  600 
feet  from  the  outlet  is  11.36  feet  above  datum  plane, 
while  the  outlet  is  7  feet  above,  making  a  total  fall  of 

11.36—7  =  4.36  feet. 
If  it  is  decided  to  give  the  drain  a  fall  of  .24  foot, 


Laying    Out   Drains  479 

or  2.88  inches  per  100  feet,  it  will  be  necessary  to  place 
the  bottom  of  the  tile,  at  600  feet  from  the  outlet, 

6  X. 24  =  1.44  feet 
higher  than  the  outlet;  that  is, 

7+1.44  =  8.44  feet 

above  datum  plane  ;  but  as  the  surface  of  the  ground 
at  the  600 -foot  station  is  11.36  feet  above  this  plane, 
as  given  in  the  table,  it  is  clear  that  the  ditch  must 
be  dug  at  this  place 

11.36  —  8.44  =  2.92  feet 

deep,  as  written  on  the  finder  stake  in  Fig.  157,  and 
as  given  in  the  table  of  field  notes  in  the  column 
headed  "depth  of  ditch." 

Since  the  grade  line  rises  .24  foot  per  100  feet  and 
.12  foot  per  50  feet,  the  data  in  the  table  under 
"grade  line"  are  obtained  by  adding  .12  foot  to  7 
feet,  the  distance  of  the  outlet  above  datum,  for  the 
50 -foot  station ;  twice  .12  foot  to  the  second  or 
100 -foot  station,  etc. 

The  numbers  in  the  column  of  differences  are 
obtained  by  subtracting  the  front -sight  from  the  back- 
sight, taken  with  each  setting  of  the  level,  and  these 
differences,  added  to  the  height  of  the  lower  station, 
give  the  elevation  of  the  higher  station  above  datum 
plane,  thus: 

4  — 3. 87  =.13  feet; 

and  this  amount,  added  to  the  height  of  the  back- 
sight station,  gives 

10 +  .13  =  10. 13  feet 
as  the  elevation  of  the  50 -foot  station,  and  subtract 


480  Irrigation   and  Drainage 

ing  from  this  elevation  that  of  the  bottom  of  the 
proposed  ditch  at  this  place,  there  is  obtained 

10.13—7.12  =  3.01  feet, 

or  the  depth  which  the  ditch  must  be  dug  at  this 
station,  and  it  is  the  custom  to  write  these  depths  on 
the  finder  stakes,  to  serve  as  the  guide  to  the  ditchers 
in  digging,  as  represented  in  Fig.  157. 

These  values  are  given  in  feet  and  hundredths 
rather  than  in  feet  and  inches,  because  it  is  much 
simpler  to  make  the  calculations  in  this  way.  The 
target -rod  should  be  made  to  read  in  this  way  rather 
than  in  feet  and  inches,  and  if  the  farmer  makes  his 
own  this  may  readily  be  done  by  first  dividing  the  rod 
into  feet  and  then,  taking  a  pair  of  dividers,  set  them 
so  as  to  space  off  ten  equal  divisions  within  each  foot. 
The  tenths  of  a  foot  may  then  be  subdivided  in  the 
same  manner  into  ten  equal  divisions,  or  hundredths 
of  a  foot. 

Where  a  level  without  a  telescope  is  used,  the 
measuring  rod  should  be  provided  with  a  sliding 
target,  as  shown  in  Figs.  153  and  158,  which  may  be 
moved  up  and  down  by  the  target  man,  as  directed,  to 
mark  the  elevation  indicated  by  the  instrument.  The 
best  target  is  provided  with  an  opening  in  front  of  the 
rod,  which  permits  the  figures  to  be  seen  at  the  junc- 
tion of  the  cross  lines  of  the  target. 

In  taking  the  elevations,  the  target -rod  should 
always  be  set  upon  the  grade  peg,  and  all  subsequent 
measurements  in  digging  should  also  be  made  from 
these  pegs,  which  are  driven  in  flush  with  the  surface, 


Changing   Grade  481 

not   only  that  they  may  represent   its   true  level,  but 
also  to  avoid  danger  of  the  pegs  being  disturbed. 


MOEE  THAN  ONE  GRADE  ON  THE  SAME  DRAIN 

It  very  frequently  happens  that  the  surface  of  the 
land  to  be  drained  is  such  as  to  make  it  impracticable 
to  lay  out  the  whole  of  a  main  or  of  a  lateral  with  the 
same  amount  of  fall  throughout.  Let  it  be  supposed 
that  at  the  end  of  the  600  feet  represented  in  Fig. 
157,  the  ground  continued  rising  backward  at  a  slower 
rate  for  500  feet  more,  as  the  figures  show  it  had 
begun  to  do,  and  that  in  the  500  feet  the  rise  was 
only  six  inches.  In  order  to  avoid  digging  too  deeply 
in  some  portions  of  the  line,  or  of  placing  the  tile  too 
close  to  the  surface  at  others,  it  is  necessary  to  change 
the  grade,  and  the  new  grade  will  be  found  by  divid- 
ing the  total  fall  .5  feet  by  5,  the  number  of  100  feet, 
which  gives  .1  foot,  and  half  this  amount  instead  of 
.12,  is  what  would  be  added  at  each  50 -foot  station, 
in  order  to  get  the  new  grade  line  elevations. 

DIGGING    THE     DITCH 

It  has  been  pointed  out  that  practice  is  required 
in  order  to  dig  a  ditch,  well,  rapidly  and  easily.  It  is 
further  necessary  to  have  suitable  tools  for  the  pur- 
pose. First  in  importance  is  the  ditching  spade,  two 
forms  of  which  are  represented  in  Fig.  158.  These 
spades  have  blades  18  inches  long,  narrower  than  the 
common  tool,  and  strongly  curved  forward,  to  give 

EE 


482 


Irrigation   and   Drainage 


greater  stiffness,  and  to  permit  them  to  be  thin  and  light. 
The  solid  blade  gives,  better  satisfaction  generally  than 
the  other  form  shown  in  the  cut. 

Besides  the  spade,  there  must  also  be  the  tile   hoe, 
or  scoop,  for  cleaning  out   and  grading  the  bottom  of 


Fig.  158.     Some  drainage  tools. 

the  ditch,  fitting  it  for  the  tile,  different  widths  being 
used  for  different  tiles,  as  shown  in  the  cut.  Some  of 
these  scoops  are  made  with  adjustable  handles,  per- 
mitting the  blade  to  be  set  at  any  desired  angle,  so 
as  to  be  used  from  the  last  spading  of  earth  in  the 
ditch  or  from  the  top. 


Fig.  159.    Commencing  a  ditch' 


Fig.  160.    Removing  the  last  two  spadings  from  the  ditch. 


Fig.  161.    Bringing  the  ditch  to  grade  line  with  tile  hoe. 


Fig.  162.    Placing  tile  with  tile  hook. 


Digging    the    Ditch  485 

When  digging  begins,  a  strong  line  is  stretched 
about  4  inches  back  from  the  side  of  the  ditch  and  a 
narrow  cutting  made,  seldom  necessarily  more  than  12 
inches  wide,  as  shown  in  Fig.  159,  the  effort  being  to 
remove  as  little  earth  as  possible.  The  sides  are  cut 
true  to  line  to  begin  with,  and  maintained  so  to  the 
bottom,  in  order  that  a  straight  bed  may  be  finished 
to  receive  the  tiles.  When  the  ditch  is  deeper  than 
4  feet,  it  is  necessary  to  make  it  a  little  wider  at  the 
top  but  not  much,  as  will  be  seen  in  Figs.  160  and  161, 
where  the  first  shows  the  men  in  line  cutting  a  ditch 
4.5  to  5  feet  deep,  while  the  second  figure  shows 
another  man  following  with  the  tile  hoe,  working  from 
the  top,  cleaning  out  the  bottom  and  bringing  it  to 
grade  line.  The  line  which  is  seen  in  Fig.  161, 
stretched  along  the  ditch,  is  placed  parallel  with  the 
grade  line  some  whole  number  of  feet  above  it,  and  is. 
used  by  the  man  to  measure  from  when  finishing  the 
bottom.  The  line  is  a  slender  but  strong  cord,  which 
may  be  stretched  tightly,  so  as  not  to  sag.  In  the 
case  in  question,  the  man  determined  his  depths  with 
the  measuring  rod  in  the  foreground,  his  long  expe- 
rience enabling  him  to  dispense  with  a  sliding  arm, 
which  is  generally  used,  forming  a  right  angle  with 
the  rod  and  long  enough  to  reach  the  grade  line.  In 
Fig.  162,  the  last  man  is  using  the  tile  hook,  shown 
second  from  the  right  in  Fig.  158,  to  lay  the  tile  in 
place.  This  ditch,  although  for  6 -inch  tile,  laid  4.5 
to  5  feet  deep,  is  scarcely  more  than  15  inches  wide  at 
the  top,  as  the  length  of  the  tile  placed  across  the 
ditch  for  a  scale  shows. 


486  Irrigation   and   Drainage 

These  men  never  get  into  the  bottom  of  the  ditch,  and 
yet  the  tile  are  laid  with  great  accuracy  and  turned 
about  with  the  hook  until  close  fitting  joints  are  secured. 

It  is  preferred  by  some  to  lay  the  tile  by  hand, 
the  operator  standing  on  the  tile,  which  are  covered 
with  earth  4  to  6  '  inches  deep  as  rapidly  as  placed, 
using  the  wet  clay  last  thrown  out,  or  some  taken 
from  the  side  of  the  ditch,  which  is  thoroughly 
worked  in  about  the  tile,  care  being  taken  not  to  get 
them  out  of  alignment.  By  whatever  method  the  tile 
are  laid,  the  greatest  care  must  be  observed  in  secur- 
ing close  joints  and  in  covering  them,  to  see  that 
they  do  not  become  displaced. 

The  work  should  begin  at  the  outlet  with  the  lay- 
ing of  the  main,  and  proceed  backward  to  the  first 
lateral,  when  this  should  be  started  and  the  junction 
made  at  once,  laying  two  or  three  tile  of  the  lateral 
before  proceeding  further  with  the  main.  If  junction 
tile  are  not  used,  the  opening  through  the  walls  for 
the  connection  is  made  with  a  small  tile  pick  with  a 
sharp  point,  and  great  care  should  be  taken  to  make 
a  close  connection  by  shaping  and  fitting  both  pieces 
together  and  covering  the  joint  with  stiff  clay,  well 
packed  about  it. 

If  for  any  reason  the  line  of  tile  is  left,  as  at 
night  or  over  Sunday,  the  open  upper  end  should  be 
plugged  with  a  bunch  of  grass  or  covered  with  a 
board,  to  prevent  dirt  being  washed  into  the  line  in 
case  of  rain.  When  the  end  of  the  line  is  reached, 
the  opening  of  the  last  tile  should  be  closed  with  a 
brick  or  stone. 


Filling    the   Ditch 


487 


It  is  very  important  to  get  the  dirt  well  filled  in 
about  the  tile  and  at  the  same  time  well  packed,  in 
order  that  large  open  water  channels  may  not  exist 
through  which  streams  of  water  may  flow  in  sufficient 
volume  to  carry  silt  into  the  tile  through  the  joints, 
and  also  in  order  that  open  channels  may  not  exist 
outside  and  under  the  tile  along  which  streams  may 
gather  and  flow.  The  clay  soil,  usually  last  taken  out 
of  the  ditch,  is  the  best  for  this  purpose. 


Fig.  163.    The  start  and  finish  of  tile  draining. 

Various  methods  of  filling  the  ditch,  after  the  first 
covering  of  the  tile,  are  in  use,  and  Fig.  163  repre- 
sents one,  where  a  plow  is  drawn  by  a  team  working 


488  Irrigation   and  Drainage 

on  a  long  evener.  Where  a  road  scraper  is  available, 
this  makes  a  good  tool  for  finishing  up  with  after 
the  line  is  filled  enough  to  cross  with  the  team. 
Another  method  of  filling,  where  the  work  is  done  by 
hand,  is  to  tie  a  rope  to  the  handle  of  a  broad  scoop, 
which  is  worked  by  a  man  across  the  ditch,  while 
another  guides  the  shovel  as  though  not  assisted  by 
the  man  with  the  rope.  In  this  way  the  dirt  is  filled 
in  rapidly. 

Still  another  method  is  to  use  a  team  on  a  wide 
board  scraper  provided  with  handles,  drawing  it  toward 
the  ditch,  the  team  being  attached  by  means  of  a  long 
rope  and  working  on  the  opposite  side  of  the  ditch, 
the  filling  being  done7  by  driving  forward  and  then 
backing,  the  man  holding  the  scraper  pulling  the  tool 
back. 

When  quicksand  is  encountered  in  laying  tile,  it 
may  be  necessary  to  brace  the  sides  of  the  ditch  to 
prevent  caving,  when  digging.  This  may  be  done  by 
driving  sticks  in  between  two  pieces  of  board,  thus 
holding  them  against  the  opposite  sides  of  the 
ditch.  It  is  occasionally  true  that  the  bottom  is  so 
soft  from  quicksand  that  the  tile  cannot  be  laid  to 
grade,  and  in  such  cases  a  fence  board  may  be 
placed  on  the  bottom  and  the  tile  laid  upon  this. 
In  .other  cases  the  ditch  may  be  dug  a  little  below 
grade  line,  and  the  bottom  covered  with  clay,  if  that 
is  available,  so  as  to  form  a  foundation  upon  which 
to  place  the  tile.  It  will  sometimes  be  true  that  a 
quicksand  spot  will  become  sufficiently  firm  to  lay 
across  if  it  is  permitted  to  drain  three  or  four  days, 


Cost   of   Underdrawing  489 

and  the  level  of  the  ground  water  be  thus  lowered. 
The  reason  for  this  is  that  the  quicksand  character 
is  due  to  the  water  being  forced  up  through  the  fine 
sand,  which  has  little  adhesion  between  its  grains, 
and  the  water  tends  to  float  the  sand,  thus  causing  it 
to  run  with  unusual  freedom  ;  but  when  the  water  is 
given  time  to  drain  away,  so  that  the  sand  is  no 
longer  full  of  it  above  the  bottom  of  the  ditch,  it 
becomes  firm,  and  the  tile  may  then  be  laid. 

COST    OF    UNDERDRAINING 

It  is  not  possible  to  give  the  cost  of  draining  land 
without  knowing  all  of  the  details  which  go  to  make 
up  the  total  expense ;  but  certain  general  statements 
may  be  made,  which  will  enable  any  one  to  compute 
for  himself  what  the  cost  is  likely  to  be. 

In  the  case  represented  by  Figs.  159  to  163,  the 
work  was  done  by  a  professional  drainage  engineer  at 
an  average  cost  of  $3  per  100  feet  for  digging  and 
laying  the  tile,  and  30  cents  per  100  feet  for  filling 
the  ditches,  thus  making  the  labor  after  the  tile  had 
been  placed  upon  the  ground  $3.30  per  100  feet, 
including  the  board  of  the  men.  The  ground  drained 
in  this  case  was  such  as  to  represent  about  average 
conditions,  where  the  spade  may  be  readily  put  into  the 
soil  with  the  pressure  of  the  foot,  where  no  stones  or 
quicksands  are  encountered,  and  where  the  main  has 
a  depth  of  3  to  5  feet,  and  the  laterals  an  average 
depth  of  3  feet.  In  the  case  represented  in  Fig.  141, 
Mr.  Elliot  gives  the  cost  of  the  -  different  items  as 
expressed  in  the  table  which  follows: 


490  Irrigation   and   Drainage 

Cost  of  main  drains  per  1,000  feet 


No. 

of  feet 

Size 

Depth 

Tile 

Digging,  laying 
and  filling         Total 

Cost 
per  rod 

1 

,000 

7 

in. 

5 

ft. 

$60.00 

$37:20        $97. 

20 

$1.60 

2 

,700 

6 

in. 

5 

ft. 

40.00 

36, 

.60 

206. 

82 

1.26 

850 

5 

in. 

4 

ft. 

30.00 

24 

.20 

46 

07 

.89 

Cost 

of  lateral 

drains 

8 

,280 

4 

in. 

3 

.5  ft. 

$20.00 

$20, 

,00 

$331. 

20 

$0.66 

7 

,030 

3 

in. 

3 

ft 

13.20 

20 

.00 

233. 

40 

.55 

Total $914.69 

It  will  be  seen  from  this  table  that  the  cost  of 
draining  8()  acres,  as  represented  in  the  figure,  averaged 
$11.43  per  acre  where  everything  was  counted.  It 
will  be  seen  that  the  cost  of  mains  was  from  two  to 
three  times  as  much  as  laterals  of  3 -inch  tile,  and 
hence,  that  the  larger  and  longer  the  mains  must  be 
made  the  more  expensive  relatively  the  draining  will  be. 

Cost  of  mains  per  100  feet 


5 -inch 


6 -inch 


7 -inch 


8-inch 


Depth  of  ditch 

and  laying 

Cost  of  tile 

ditch 

per  100  feet 

>3  feet 

$1.50 

$3.00 

$0.30 

$4.30 

4  feet 

2.00 

3.00 

.42 

5.42 

5  feet 

3.00 

3.00 

.60 

6.60 

6  feet 

4.50 

3.00 

.75 

8.  "25 

3  feet 

1.50 

4.00 

.30 

5.80 

4  feet 

2.10 

4.00 

.42 

6.52 

5  feet 

3.00 

4.00 

.66 

7.66 

6  feet 

5.10 

4.00 

.78 

9.88 

3  feet 

1.80 

6.00 

.36 

8.16 

4  feet 

2.40 

6.00 

.48 

8.88 

5  feet 

3.00 

6.00 

.72 

9.72 

6  feet 

5.70 

6.00 

.90 

12.60 

3  feet 

1.92 

8.50 

.42 

10.84 

4  feet 

2.58 

8.50 

.54 

11.62 

5  feet 

3.90 

8.50 

.78 

13.18 

6  feet 

6.00 

8.50 

1.00 

15.52 

Peat   Lands  491 

We  quote  this  table  regarding  the  cost  of  mains, 
as  estimated  by  Mr.  Elliot,  where  the  price  paid  for 
good  ditchers  is  $2  per  day;  but  in  this  estimate  the 
board  of  the  men  is  not  included,  neither  is  the  cost 
of  hauling  the  tile  from  the  station  to  the  field. 

i  This  same  writer  estimates  the  cost  of  3 -inch  lat- 
erals, placed  3  to  3.5  feet  deep,  at  $2  per  100  feet  for 
the  digging,  laying  and  filling,  and  tile  at  .the  present 
writing  would  add  another  dollar,  making  $3  per  100 
feet,  not  including  board  or  hauling  the  tile. 

The  cost  per  acre  will,  of  course,  vary  with  the 
distance  between  lines  of  tile,  and  will  increase  very 
nearly  in  proportion  to  the  number  of  feet  of  tile 
used. 

PEAT   LANDS 

There  are  many  marshes  underlaid  by  beds  of  peat 
not  yet  well  rotted ;  peat  so  free  from  silt  and  so 
fibrous  in  texture  that  when  dry  it  could  be  used  for 
fuel.  Where  fields  are  underlaid  by  such  beds  having 
a  depth  of  three  or  more  feet,  they  are  not  likely  to 
become  at  once  productive  if  well  drained.  On  the 
other  hand,  where  the  peat  deposit  is  only  from  6  to 
18  inches  deep,  there  are  likely  to  be  better  returns 
from  thorough  drainage. 

In  the  first  class  of  cases  referred  to,  underdrain- 
ing  is  not  usually  to  be  recommended  as  the  first 
step  toward  improvement.  The  difficulty  lies  in  the 
fact  that  when  peat  beds  are  .drained  they  shrink 
greatly  in  volume,  thus  lowering  the  surface  in  a 


492  Irrigation  and  Drainage 

marked  degree,  and  if  underdrains  were  laid  at  once, 
the  lines  of  the  tile  would  ultimately  be  found  too 
close  to  the  surface.  It  is,  therefore,  usually  better 
in  such  cases  to  drain  first  with  open  ditches,  plac- 
ing them  where  ultimately  they  may  be  deepened 
and  converted  into  underdrains.  The  surface  ditch- 
ing will  dry  out  the  marsh  to  a  considerable  extent. 
and  permit  the  needed  decay  and  shrinkage  of  the 
peat  to  take  place,  although  several  years  may  be 
required  for  this. 

If  the  peat  is  very  coarse  and  thick,  and  if  little 
vegetation  grows  upon  it,  it  may  be  well  to  burn  it 
over  several  times  when  not  too  dry,  in  order  to 
increase  the  silt  and  ash  in  the  soil  and  to  hasten 
the  shrinkage.  The  ash  thus  formed  will  so  much 
improve  the  texture  of  the  surface  as  to  very  mate- 
rially assist  in  getting  a  crop  started  upon  the  area. 

It  is  very  important  to  get  a  crop  started  upon  the 
soil  as  soon  as  practicable,  because  this  greatly  facili- 
tates and  hastens  the  rate  of  decay.  This  should 
be  done,  even  though  it  may  not  be  remunerative  in 
any  other  way  than  that  of  improving  the  texture  of 
the  soil. 


INDEX 


Acre-foot,  239. 

Acre-inch,  239. 

Aermetor,  windmill,  313;  pump,  316. 

Air,  in  the  soil,  7, 182;  humidity,  40,  44, 
50;  required  by  clover,  49;  by  corn, 
185;  interferes  with  percolation,  333; 
need  of  in  soil,  182,  370,  418;  lack  of 
in  puddled  soil,  334:  changes  in  tem- 
perature and  pressure  influence  ven- 
tilation, 420. 

Alfalfa,  roots,  233;  irrigation,  237,  346, 
348 ;  utilizing  waste  water,  379. 

Algeria,  irrigation,  85,  238  ;  duty  of 
water  in,  212;  artesian  wells,  85. 

Alkali,  composition,  278 ;  accumulation, 
223,  266,  270,  272,  274,  284;  cause  of  in- 
juries, 270,  416;  accumulation  by  in- 
tensive farming,  274, 284;  amounts  in- 
jurious, 275,  278;  develops  soonest  in 
clay  soil,  286 ;  correction  by  land 
plaster,  280,  284,  287;  distribution  in 
soil,  282;  influenced  by  tillage,  284; 
influenced  by  roots,  284;  cause  of 
abandonment  of  ancient  irrigation 
systems,  289;  geographical  distribu- 
tion, 272;  formed  by  canal  seepage, 
294 ;  soils  which  soonest  develop 
alkali,  286;  cause  of  puddling,  335. 

Alkali  lands,  269,  416;  alum  spots,  269; 
soluble  salts,  269,  276  :  character  of 
vegetation,  281;  land  plasters,  280, 284; 
improvement  by  drainage,  223,  284, 
288;  ultimate  remedy  drainage,  288. 

Alkali  salts,  266;  kills  barley,  276;  see 
Alkali. 

Alkali  water,  unsuitable  for  irrigation, 
266,  284,  285;  correction  before  use, 
287. 


Alum  spots,  269. 

Animal  power  for  irrigation,  328. 

Ants,  work  in  soil  ventilation,  419. 

Apple,  roots,  231. 

Argentina,  irrigation,'87. 

Arid  climate,  efficiency  of  rainfall,"  4, 
104;  accumulation  of  alkalies,  272. 

Armenia,  irrigation,  84. 

Artesian  wells,  in  Sahara.  85;  in  Ha- 
waii, 86. 

Assyrian  irrigation,  67. 

Australia,  irrigation,  81. 

Austria-Hungary,  irrigation,  75. 

Baker,  J.  O.,  466. 

Barker,  F.  C.,  236. 

Barley,  water  used,  21,  24,  34,  46,  235; 
available  rainfall,  124  ;  yield,  129; 
yield  increased  by  irrigation,  110  ; 
second  crop,  130,  179;  number  of  irri- 
gations, 235;  on  alkali  lands,' 276. 

Barrens,  114. 

Basin  irrigation,  387,  390  ;  Egypt,  288. 

Bavaria,  irrigation,  76. 

Bear  valley  dam,  302. 

Belgium,  water-meadows,  362. 

Blackberry  irrigation,  383. 

Black  marsh  soil,  mulches,  201 ;  alkali, 
269,  273;  vegetation,  281. 

Boussingault,  49. 

Breathing  of  plants,  47,  182;  pores,  51. 

Bucket  pump,  316,  319,  325. 

Busca  canal,  210. 

Cabbage,  irrigation,  387  ;  yield  in- 
creased by  irrigation,  110;  effect  of 
supplementing  rainfall  in  Wisconsin, 
175. 


(493) 


494 


Index 


Canal,  ancient,  67;  Busca,210;  Ceylon, 
81;  Doab,  80;  Egyptian,  68;  Eu- 
phrates, 68;  Forez,  72  ;  Gattinara, 
210;  Great  Imperial,  71;  Ganges  sys- 
tem, 80;  India,  79  ;  Indus  valley,  81; 
Ivrea,  209;  West  and  East  Jumna,  80; 
Kern  Island,  292 ;  Nahrawan  and 
Dyiel,  69;  Nira,  78  ;  Santa  Ana,  297; 
Sirhind,291;  Soane  circle,  80 ;  cement, 
300,  412  ;  dangers,  295  ;  sewage,  410, 
412;  stone,  410. 

Canvas  dam,  339,  341,  355. 

Cape  Colony  irrigation,  85. 

Capillary  spread  of  water,  161,  330,  375. 

Capillarity,  rate  in  sand  and  loam,  148. 

Carbon  dioxide,  consumed  by  clover, 
49  ;  possible  insufficiency  in  close 
planting,  185;  in  soil  ventilation,  419; 
consumed  by  maize,  185. 

Carpenter,  L.  G.,  water-meadows,  219; 
seepage  from  reservoir,  323  ;  water 
divisor,  245. 

Catch  crops,  152. 

Celery,  irrigation,  385. 

Ceylon,  irrigation,  81. 

Checks,  345,  348,  350. 

Check  ridges,  346,  348. 

Child,  J.T.,  83. 

China,  irrigation,  71,  82. 

Chinese  irrigation,  387. 

Clay  soil,  develops  alkali,  286. 

Climate,  arid,  4,  104;  for  irrigation 
practice,  89;  for  sewage  irrigation, 
404;  lainfall  needed  for  humid  and 
subhumid,  121. 

Clover,  water  used,  '24,  34,  36,  41,  46 ; 
irrigation,  110,  130,  179  ;  on  sandy 
soil,  169. 

Colmatage,  94,  261. 

Corn.     See  Maize. 

Cotton,  duty  of  water,  211. 

Craigentinny  meadows,  16,  92,  254,  403. 

Cranberries,  duty  of  water,  220;  irriga- 
tion, 365. 

Cranefield,  P.,  irrigation  with  cold 
water,  251. 


Crops,  yields,  125,  126,  174,  175,  177,  179, 
187,  190,  216 ;  for  sewage  irrigation, 
409,  411. 

Cucumbers,  irrigation,  388. 

Cultivation.     See  Tillage. 

Cultivator,  orchard,  381;  potatoes,  354. 

Croyden,  sewage  irrigation,  411,412, 413. 

Dam,  submerged,  305;  canvas,  339,  341, 
355;  Bear  valley,  302;  Vir  weir,  78. 

Deherain,  276. 

Delaware  river  water,  252. 

Deiiitrification,  334,  370;  in  sewage,  403; 
lessened  by  drainage,  420. 

Denmark,  irrigation,  75. 

De  Vries,  277. 

Divisors,  244. 

Ditches,  depth  and  grade,  477;  bringing 
to  grade,  484  ;  digging,  481  ;  com- 
mencing and  finishing,483 ;  filling,487. 

Dooii,  for  lifting  water,  328. 

Drainage,  principles,  415  ;  influence  on 
fertility,  13;  remedy  for  alkali  lands, 
284,  288;  made  necessary  by  seepage 
from  canals,  295;  of  water-meadows, 
360,  364;  of  cranberry  marshes,  366, 
368;  rice  fields,  369,  371;  necessity, 
416;  ventilates  soil,  418,  419;  lessens 
denitrification,  420;  increases  avail- 
able moisture,  13,  422;  makes  soil 
warmer,  423  ;  where  needed,  428  ; 
sinks  and  ponds,  460 ;  intercepting 
underflow,  459;  intercepting  surface 
water,  461;  use  of  trees,  462  ;  use  of 
windmill,  463;  levels,  470;  tools,  482; 
peat  lands,  491. 

Drainage  levels,  470  ;  use,  471,  473,  477. 

Drainage,  surface,  464,  466. 

Drains,  depth,  436,  442  ;  distance  apart, 
437,  439  ;  used  in  sub-irrigation,  400; 
entrance  of  water,  438,  445  ;  kinds, 
443  ;  rate  of  entrance  of  water,  446  ; 
use  of  collars,  446  ;  fall  or  gradient, 
447  ;  size  of  mains,  450,  452  ;  size  of 
laterals,  450,  452;  outlets,  453;  ob- 
structions, 455  ;  laying  out  systems, 


Index 


495 


456  ;  cost,  458,  489  ;  staking  out,  476  ; 
determining  depth  and  grade,  477  ; 
changing  grade,  481 ;  in  peat  lands, 
491;  surf  ace,  464,  466. 

Drill,  seed,  167. 

Drought,  frequency  and  length  of  pe- 
riods, 106,  108,  109,  126. 

Durance,  fertility  of  water,  260  ;  head- 
gate,  263. 

Duty  of  water,  212,  213,  214,  236  ;  maxi- 
mum, 196  ;  least  amount  for  paying 
crop,  95;  average,  214  ;  highest  prob- 
able, 198,  215;  influenced  by  crop,  199, 
227  ;  influenced  by  soil,  200,  203  ;  in. 
fluenced  by  rainfall,  204  ;  influenced 
Iby  subsoil,  205 ;  influenced  by  cultiva- 
tion, 206  ;  influenced  by  closeness  of 
planting,  207;  influenced  by  fertility, 
207  ;  influenced  by  frequency  of  wa- 
tering, 207  ;  in  Egypt,  211 ;  France, 
211;  Italy,  209;  Spain,  211;  for  sugar 
cane,  214  ;  rice,  217;  for  water-mead- 
ows, 219 ;  for  cranberries,  220  ;  in 
sub-irrigation,  396,  400. 

Dry  farming,  western  United  States, 100. 

Dykes,  261,  306,  366,  369,  428  ;  sluices 
373. 

Earthworms,  in  soil  ventilation,  419. 

Ebermayer,  temperature  in  germina- 
tion, 248,  425. 

Edinburgh,  sewage  irrigation,  92,  254, 
403;  Evening  Dispatch,  257. 

Egypt,  irrigation,  67,  84,  260,  262,  328  ; 
duty  of  water,  211 ;  prevention  of 
alkali,  288. 

Elliott,  C.  G.,450,  451,  489,  490. 

England,  irrigation,  76,  360,  409,  411, 
413. 

Euphrates,  canals,  68. 

Evaporation,  from  plants,  40,  42  ;  from 
clover  field,  50;  rate  from  soil,  98, 
148 ;  from  rolled  ground,  167  ;  in- 
influenced  by  windbreaks,  169 ; 
through  mulches,  201. 


Fallowing,  relation  to  soil  moisture, 
153,  162,  163,  223. 

Fertility,  influenced  by  drainage,  13; 
by  cultivation,  370  ;  affects  duty  of 
water,  207. 

Fertilization,  by  irrigation,  16,  92,  251, 
259. 

Fertilizers,  in  sewage,  4Q4;  in  river  wa- 
ter, 252,  253,  259,  260. 

Field  irrigation,  by  flooding,  338,  345  ; 
in  checks,  347,  350  ;  by  furrows,  352, 
354,  358;  sub-irrigation,  399. 

Filtration  of  sewage,  404. 

Flume  box,  375. 

Flynn,  duty  of  water,  212. 

Flooding,  338;  dry  soil,  333  ;  danger  of 
puddling,  335;  systems,  340  ;  by  run- 
ning water,  340;  on  steep  slopes,  342; 
permanent  meadows,  344  ;  in  checks, 
345,  347,350;  preparatory  to  planting, 
353;  to  prevent  frost,  365;  to  destroy 
insects,  365;  rice  fields,  369;  to  germi- 
nate red  rice,  371 ;  orchards,  383;  gar- 
dens, 386,  390;  lawns  and  parks,  392. 

Foot  ditch,  378. 

Foote,  A.  D.,  spillbox,  245. 

Forez  canal,  72. 

France,  irrigation,  '72  ;  duty  of  water, 
211;  water-meadows,  219. 

Fruit,  irrigation,  383. 

Furrows,  capillary  spreading,  161,  330  ; 
distance  apart,  336  ;  gradient,  338  ; 
distributing,  340,  342. 

Furrow  irrigation,  352,  358;  on  sandy 
soil,  330  ;  on  fine  soil,  332  ;  puddles 
soil  less,  336;  on  steep  slopes,  338  ; 
for  potatoes,  354  ;  in  alternate  rows, 
354,  357  ;  for  bed  flooding,  359  ;  for 
orchards,  375;  ring-furrows,  380  ;  for 
small  fruits,  383  ;  for  gardens,  385, 
387,  389  ;  for  melons,  388  ;  requires 
less  water,  387. 

Garden,  irrigation,  384;  sewage  garden, 

407. 
Gas-engine,  324;  cost  of  running,  324. 


496 


Index 


Gasoline  engine,  305,  324,  393  ;  cost  of 
running,  324. 

Gasparin,  ratio  of  grain  to  straw,  96  ; 
salt  in  soil,  276. 

Gennevilliers,  sewage  irrigation,  389, 
411;  model  gardens,  408  ;  sewage  hy- 
drant, 410  ;  stone  canal,  410  ;  health- 
fulness,  413. 

Gipps,  F.  S.,  66. 

Goff,  E.  S.,  irrigation  of  strawberries, 
181;  depth  of  roots,  231. 

Goodale,  G.  A.,  51. 

Goss,  Arthur,  253,  259. 

Grade  pegs,  478. 

Grader,  350,  351,  352. 

Grading  for  irrigation,  346,  348,  351. 

Grain,  irrigation,  340,  342,  344,  346  ;  dry 
farming,  103  ;  harrowing  and  rolling, 
146  ;  thin  seeding,  163  ;  duty  of  water, 
198. 

Grapes,  roots,  232;  frequency  of  irriga- 
tion, 238. 

Grass,  observed  yields,  127;  on  sewage 
meadows ,  92, 409 ;  on  water-meadows , 
219  ;  irrigation,  340,  342, 346  ;  in  lawns 
and  parks,  392. 

Gravel,  silted,  263. 

Greeley,  Colorado,  irrigation  of  grain, 
340  ;  potatoes,  354. 

Green  manure,  151. 

Ground-water,  origin,  429  ;  relation  to 
surface,  431,  435  ;  lines  of  flow,  432, 
438 ;  discharge  into  streams,  433  ; 
gradient,  435;  changes  in  level,  440. 

Growth  of  river,  433. 

Grunsky,  C.  E.,  292,  349. 

Hall,  Wm.  H.,  211. 

Hare,  R.  F.,  253. 

Harrington,  M.  W.,  99. 

Harvey,  F.  H.,  309. 

Hawaii,  irrigation,  86 ;  duty  of  water 
for  sugar  cane,  214. 

Hay,  yields,  127,  178  ;  need  for  irriga- 
tion, 128  ;  second  crop,  130, 179  ;  duty 
of  water,  215. 


Hazzard,  W.  M.,  rice  irrigation,  238. 
Health,  influence  of  sewage,  256,  295, 
Hellriegel,  96.  [413. 

Hilgard,   E.  W.,    peculiarities  of   arid 

soils,  6,  229  ;  alkali  lands,  269,  276  ; 

composition  of  alkali  salts,  278  ;  land 

plaster  for  alkali  lands,  280,284;  roots 

in  arid  soils,  6,  229. 
Hinton,  R.  J.,  78,  81. 
Hollis,  Geo.  S.,  85. 
Humidity  of  air,  40,  44,  50. 
Hunter,  intertillage,  157.  [410. 

Hydrants,   distributing,  301  ;    sewage, 
Hydraulic  rams,  310. 

Inch,  acre,  240;  miner's,  241.  [291. 

India,  irrigation,  77, 328 ;  Sirhind  canal, 

Insects,  destroyed  by  irrigation,  218, 221. 

Intertillage,  157. 

Irrigation  culture,  66. 

Irrigation,  antiquity,  66;  extent,  72;  ob- 
jects, 91;  climatic  conditions,  89;  fre- 
quency, 107,  212,  223,  234,  236  ;  insuf- 
fiency  of  water,  117;  amount  of  water, 
196,  208,  212,  213,  214,  236  ;  late  crops 
difficult  to  grow  without,  129;  in- 
crease of  yield  in  humid  climates,  171; 
closer  planting  possible,  181 ;  tillage 
as  a  substitute,  117 ;  character  of 
water,  248  ;  temperature,  248  ;  num- 
ber of  irrigations  required,  235;  fer- 
tilizing value,  251 ;  supplying  water, 
290  ;  methods  of  application,  329; 
sewage,  403. 

Italy,  irrigation,  71,  359;  duty  of  water, 
209,  219  ;  water-meadows,  219  ;  mar- 
cite,  219;  sewage;  220. 

Ivrea  canal,  209. 

Japan,  irrigation,  82. 
Java,  irrigation,  86. 

Kansas,  yields  of  grain,  103;  rainfall. 

103. 

Kern  Island  canal,  292. 
Kiihn,  Jul.,  454. 


Index 


497 


Land  plaster,  for  a^alies,  280,  284,  287. 

Laterals,  subdivision,  223;  length  and 
size,  452  ;  outlet,  454  ;  junction,  464; 
cost,  490. 

Lawn,  irrigation,  391;  cost  of  plant,  393; 
method,  395. 

Laveleye,  E.,  75. 

Leaching,  222;  may  assist  nitrification, 
12;  prevents  alkali,  223,  284,  288;  nec- 
essary, 275. 

Leveling,  methods,  471, 473,  477. 

Levels,  methods,  469;  instruments,  470. 

Lois  Weedon,  system  of  intertillage,157. 

Lombardini,  260. 

Lombock,  irrigation,  87. 

Lettuce,  irrigation,  385. 

Lew  Chew,  irrigation,  83. 

Loughridge,  R.  H.,  229. 

Madagascar,  irrigation,  86. 

Madeira,  irrigation,  86. 

Maeris,  Lake,  66. 

Mains,  451,  457;  size,  451;  length,  452; 
cost,  490. 

Maize,  water  used,  21,  24,  38,  39,  41,  46, 
60,  177,  234  ;  flint  and  dent,  40,  184 ; 
roots,  61, 160;  yields  and  rainfall,  109; 
yield  increased  by  irrigation,  110, 177; 
observed  yields,  126,  177,  190;  varia- 
tion of  yield  with  soil  moisture,  144 ; 
rain  of  growing  season,  124  ;  maxi- 
mum limit  of  yield,  187;  need  for  air, 
182,185;  close  planting,  184,193;  yields 
with  varying  closeness  of  planting, 
190;  duty  of  water,  211, 215;  frequency 
of  irrigation,  235. 

Mangon,  water  on  water-meadows,  219. 

Marcite,  219. 

Markus,  E.>  duty  of  water,  203. 

Meadows,  water,  16,  92,  219,  251,  359; 
Craigentinny,  16, 92,  254, 403;  English, 
76,  360;  Italian,  362;  Belgian,  362; 
mountain,  365;  marcite,  219;  duty  of 
water,  219;  sewage,  220,  254;  mulch- 
ing, 146;  irrigation,  frequency,  237. 

Measurement  of  water,  239;  units,  239; 


methods,  241;  by  time,  242;  subdivi- 
sion of  laterals,  243  ;  with  divisors, 
244;  modules,  245. 

Melons,  irrigation,  388. 

Milan,  sewage  irrigation,  220. 

Milk,  from  sewage  grass,  256. 

Miner's  inch,  241. 

Mississippi,  annual  discharge,  117. 

Modules,  245;  spill-box,  245. 

Mulches,  145;  of  soil,  142;  effectiveness 
in  arid  climates,  104;  lose  effective- 
ness, 145,  164;  for  meadows,  146;  in- 
fluence of  depth,  147,  206;  vary  with 
kinds  of  soil,  201;  production  after 
irrigation,  381. 

Neerpelt,  water-meadows,  362. 

Newell,  F.  H.,  irrigation,  88;  dry  farm- 
ing, 102;  run-off,  119. 

New  Jersey,  water  analyses,  252. 

New  Mexico,  frequency  of  irrigation, 
238. 

Nile,  irrigation,  67,  84,  2P2,  288;  daily 
discharge,  85;  delta,  68;  sediment  in 
water,  260. 

Nitrates,  in  artesian  waters,  85 ;  in 
river  water,  252;  in  sewage,  404. 

Nitrification,  in  arid  soils,  7;  needs  wa- 
ter, 11 ;  influenced  by  drainage,  13, 
420;  effect  of  tillage,  149,  163,  165; 
needs  oxygen,  183,  334,  370,  418. 

Nitrogen-fixing  tubercles;  233. 

Oats,  water  used,  21,  24,  31V41,  46;  rain 
of  growing  season,  124;  yields,  126; 
water  needed" ,  215. 

Oranges,  frequency  of  irrigation,  238; 
furrow  irrigation,  374. 

Orchards,  irrigation,  338, 373;  frequency 
of  irrigation,  238;  ring  furrows,  380-, 
cultivator,  381;  cultivation,  381,  383; 
sub-irrigation,  398. 

Osmotic  pressure,  63. 

Paecottah,-  327. 
Palms,  irrigation,  85. 


498 


Index 


Park  irrigation,  391. 

Peas,  water  used,  46. 

Peat  lands,  491;  warping,  262. 

Percolation    of   water,    225 ;     through 

.  sand,  113,  205;  on  duty  of  water,  203; 
through  shrinkage  cracks,  227  ;  into 
tile,  446;  loss, 330;  rate  from  tile,  400. 

Perels,  E.,  duty  of  water,  203, 212. 

Persian  wheel,  325,  328. 

Peru,  irrigation,  71. 

Phoenician  irrigation,  69.  [299. 

Pipe  line,  Redlands,  296;  redwood,  298, 

Pipes  for  lawns,  394. 

PJagniol,  salt  in  soils,  275. 

Plant  breathing,  47. 

Plant  feeding,  52,  57. 

Plant-food,  14, 15, 93, 252, 259;  developed 
by  tillage,  149;  effect  of  fallowing, 
154;  in  alkali  salts,  280,  285. 

Plant-house  experiments,  18,  35,  43; 
yields,  25,  41. 

Plowing,  fall,  131;  plowing  under  green 
manure,  151;  to  form  check  ridges, 
346. 

Plow,  for  producing  mulch,  149 ;  for 
producing  distributing  furrows,  340, 
342.  [260. 

Po,  irrigation,  72;    sediment  in  water, 

Potatoes,  irrigation,  28,  32,  35,  172,  353, 
357,  413;  water  used,  30,  37,  46,  174, 
237;  yields,  110,  357;  advantages  of 
irrigation  in  humid  climates,  172 ; 
watering  alternate  rows,  354,  357 ; 
distance  between  rows,  357;  moisture 
in  rows,  161,  200;  duty,  of  water,  215; 
number  of  waterings,  237,  356. 

Press  drill,  167. 

Puddling  of  soils,  principles  governing, 
334. 

Pumping,  with  windmill,  313,  316;  with 
engines,  324;  cost,  324,  326;  for  cran- 
berries, 368;  for  drainage,  463. 

Pumps,  with  windmill,  316,  319;  with 
engines,  324,  326,  393;  with  water 
wheels,  76,  306,  308,  309;  with  horse 
power,  325. 


Quicksand,  488. 

Rainfall,  in  arid  and  semi-arid  climate*, 
4,  6,  99,  101;  timely,  10;  of  irrigated 
countries,  89;  in  Kansas,  103;  fre- 
quency in  Wisconsin,  108  ;  like 
amounts  not  equally  effective,  101. 
115,  204 ;  relation  to  yield,  109,  125  • 
conditions  modifying  effectiveness 
110;  in  United  States,  123;  in  eastern 
United  States,  124;  amount  needed  in 
humid  regions,  121;  of  growing  sea- 
son, 124  ;  distribution  in  time  un- 
favorable to  maximum  yields,  125; 
early  rains  saved  by  tillage,  128;  af- 
fects duty  of  water,  204;  in  Colorado, 
236;  in  India,  291. 

Ramming  engine,  310. 

Rape,  irrigation,  359. 

Raspberries,  roots,  231;  irrigation,  383; 
sub-irrigation,  398. 

Read,  T.  M.,  solids  in  river  waters,  253. 

Redlands,  Cal.,  irrigation  systems,  296. 

Red  rice,  371. 

Reservoir,  distributing,  297;  construc- 
tion, 320;  sluice,  321;  circular,  322; 
seepage  and  evaporation,  323;  capac- 
ities, 323;  for  cranberries,  367;  use  in 
drainage,  464. 

Rice,  irrigation,  368;  in  Italy,  210;  in 
Egypt,  211;  South  Carolina,  238,  266, 
306,  369,  372;  duty  of  water,  217;  fre- 
quency of  irrigation,  238 ;  cultiva- 
tion, 370;  red  rice,  371;  upland,  373. 

Ridge  cultivation,  165. 

Rio  Grande,  analyses  of  water,  253, 259. 

Road  grader,  350. 

Rolling  in  relation  to  soil  moisture,  166; 
cause  of  loss  of  moisture,  167. 

Roman  canals,  70. 

Root  cap,  64. 

Root  hairs,  55;  relation  to  soil  grains, 
55;  acid  reaction,  59. 

Roots,  depth  of  penetration  in  arid 
soils,  6,  229;  shallow  in  undrained 
soil,  13;  function,  55;  absorbing  sur- 


Index 


499 


face,  55;  acid  reaction,  59;  extent  of 
surface,  59,  61,  160 ;  movement 
through  soil,  63;  superficial  develop- 
ment, 208;  depth,  200,  227,  231;  oats, 
ciover  and  barley,  60;  maize,  61; 
prune,  228;  apple,  229;  grape,  230; 
raspberry,  231 ;  strawberry,  232 ; 
alfalfa,  233.  [119. 

Run-off,  Mississippi,  117;  United  States, 

Rye  as  green  manure,  151. 

Rye  grass,  for  sewage  meadows,  409. 

Sachs,  55,  425. 

Sahara,  irrigation,  85. 

Salts,  soluble  in  alkali  land,  269,  276; 
cause  of  injuries,  270 ;  accumulate 
with  intensive  farming,  274;  amount 
injurious,  275,  278. 

Saltwirt,  276. 

Sandwich  Islands,  irrigation,  86;  duty 
of  water,  215. 

Sand,  percolation,  112,  224. 

Sandy  soils,  experiments,  32;  texture 
improved  by  irrigation,  93,  262;  re- 
tain little  water,  111,  205,  224  ;  why 
unproductive,  114;  destructive  effects 
of  winds,  168;  areas  suited  to  irriga- 
tion, 264;  furrow  irrigation,  330,  358; 
handling  water,  331. 

San  Joaquin  valley,  4,  96,  98;  flooding 
system,  348. 

Scraper,  ridging,  348,  351. 

Seaman  and  Schuske,  bucket  pump,  316. 

Second-foot,  239. 

Seed-bed,  preparation,  150,  167. 

Seepage,  coarse  soils,  203;  upland  rice 
i-ulture,  218  ;  from  canals,  244  ;  from 
reservoirs,  323. 

Sewage,  dangerous  nitrogen  com- 
pounds, 405;  agricultural  value,  406; 
need  of  wider  agricultural  use,  406, 
409  ;  in  Italy,  406  ;  Edinburgh,  403  ; 
Milan,  407;  Paris,  407;  Croyden,  411, 
412,  413. 

Sewage  effluent,  purity,  414;  bacteria, 
414. 


Sewage  grass,  wholesorneness,  256,  413. 

Sewage  irrigation,  object  sought,  403; 
Craigentinny  meadows,  16,  92,  254; 
healthfulness,  256,  405,  413;  distri- 
bution of  water,  403;  climatic  condi- 
tions favorable,  404;  report  of  Mas- 
sachusetts State  Board  of  Health. 
405;  soils  best  suited,  406;  oppor- 
tunity for  in  United  States,  407; 
model  garden,  407 ;  yield  of  grass,  409 ; 
grasses  for,  409;  crops,  409,  411. 

Sewage  purification,  405;  by  irrigation, 
405;  by  filtration,  404;  essential  con- 
ditions, 405. 

Sewage  water,  15,  92,  220,  253. 

Siam,  irrigation,  83. 

Silt  basin,  448. 

Silting  coarse  soils,  93,  260,  261;  oppor- 
tunity for  in  United  States,  264;  of 
rice  fields,  370. 

Siphon,  in  pipe  line,  296;  elevator,  310. 

Sirhind  canal,  291. 

Sluice,  for  reservoir,  261,  321,  369. 

Small  fruits,  irrigation,  383;  late  plow- 
ing, 132. 

Smith,  Baird,  duty  of  water,  209 ;  water- 
meadows,  220. 

Smith,  Rev.,  system  of  intertillage,  157. 

Smith,  Brothers,  irrigation  plant,  308. 

Soil,  water  capacity,  3,  224;  texture  in 
relation  to  rainfall,  3;  humid  and 
arid,  4;  ventilation,  11,  419;  water- 
logging, 11,  334;  sandy,  32,  111,  114, 
168,  205,  224,  264,  330,  331,  358;  silt- 
ing, 93,  260,  262,  263,  264  ;  mulches, 
201,  206;  black  marsh,  201,  281;  pore 
space,  63 ;  best  temperature,  248 ; 
alkali,  282;  clay,  286;  puddling,  prin- 
ciples governing,  334,  335  ;  washing, 
principles  governing,  337 ;  absorp- 
tion of  sewage,  404 ;  kinds  best 
suited  to  sewage  irrigation,  406. 

Soil  grains,  relation  to  root  hairs,  55; 
relation  of  size  to  drainage,  438. 

Soil  mulches,  142;  more  effective  in 
arid  climates,  105;  effectiveness,  144, 


500 


Index 


201 ;  lose  effectiveness,  145 ;  of  dif- 
ferent soils  compared,  144,  201  ; 
depth,  147, 165, 206;  frequency  of  stir- 
ring, 164. 

Soil  moisture,  advantages  of  abundant 
supply,  9;  mechanism  of  plant  sup- 
ply, 54;  effect  of  subsoiling,  134;  ef- 
fect of  fallowing,  153,  155,  162,  225;  in 
potato  rows,  161;  means  of  conserv: 
ing,  131;  conservation  by  tillage,  164; 
influence  of  rolling,  166;  loss  through 
mulches,  144,  201;  best  amount,  226. 

Soil  ventilation,  419;  need,  11;  work  of 
carbonic  acid,  419;  influence  of  drain- 
age, 418;  part  played  by  roots,  420, 
421;  influence  of  changing  air  tem- 
perature and  pressure,  420;  may  les- 
sen denitrification,  420;  may  increase 
nitrates,  420;  may  be  too  thorough, 
421. 

Soil  temperature,  248,  250,  425;  in- 
fluenced by  drainage,  423 ;  importance, 
425;  influence  on  germination,  425; 
influence  of  cultivation,  427. 

Soil  warmth,  425. 

Soil  water,  plant-food  dissolved,  14 ; 
amount  of  alkalies  carried,  278;  stag- 
nation prevented  by  drainage,  416. 

South  America,  irrigation,  87. 

South  Carolina,  rice  irrigation,  238, 
266,  306,  369,  372. 

Spain,  irrigation,  72, 238;  duty  of  water, 
211. 

Spill-box,  245. 

Spraying  lawns,  393. 

Strawberries,  irrigation,  110,  181,  384  ; 
roots,  232;  sub-irrigation,  398. 

Storer,  F.  H.,  254,  275. 

Sub-irrigation,  396;  of  clover,  179  ;  ob- 
jections and  difficulties  in  the  way, 
396,  397,  401 ;  water-meadows,  401 ; 
orchards  and  small  fruits,  401 ;  dan- 
ger of  clogging  tile  by  roots,  401 ; 
time  required,  401;  through  tile 
drains,  400 ;  conditions  necessary,  401 ; 
an  adjunct  to  drainage,  460. 


Subsoil,  affects  duty  of  water,  205. 

Subsoiling,  133 ;  effects,  139 ;  sugar 
cane,  irrigation,  214  ;  duty  of  water, 
215. 

Summer  fallowing,  153,  154,  163. 

Sunlight,  evaporation  during,  44 ;  action 
in  plant-feeding,  49;  limited  in  close 
planting,  183,  194. 

Surface  drainage,  464  ;  examples,  466  ; 
peat  lands,  491. 

Surface  tension,  57. 

Swamp  lands,  273 ;  area  in  United 
States,  415  ;  improved  by  drainage, 
416;  intercepting  underflow,  459;  in- 
tercepting surface  water,  461. 

Switzerland,  irrigation,  74,  365. 

Target-rod,  470,  471. 

Temperature  of  soil,  248  ;  subsoil 
changed  by  rains  and  irrigation,  14, 
248  ;  reduced  by  close  planting,  183  ,- 
favorable  to  sewage  irrigation,  404. 

Temperature  of  water  for  irrigation, 
250. 

Tidal  irrigation,  238,  261,  306,  369,  373. 

Tigris,  canals,  69. 

Tile,  injury  by  frost,  442  ;  for  sub-irri- 
gation, 398, 400;  size,  449,  452;  laying, 
484;  in  quicksand,  488. 

Tile-hook,  482. 

Tillage,  extent  to  which  it  may  replace 
rain  or  irrigation,  117 ;  most  which 
may  be  hoped  for  tillage,  120  ;  inap- 
plicable in  some  cases,  127;  chiefly 
saves  early  rains,  128;  may  do  harm, 
129;  late  plowing,  132;  subsoiling, 
133;  earth  mulches,  142,  164,  206; 
mulches  lose  in  effectiveness,  145; 
harrowing  and  rolling,  146,  166;  early 
tillage  important,  148  ;  plow  as  a  til- 
lage tool,  149  ;  intertillage,  157,  163  ; 
frequency  of  tillage,  164,  205  ;  depth, 
165,  206  ;  ridged  and  flat  cultivation, 
165 ;  in  rice  fields,  370 ;  after  irriga- 
tion, 381,  389 ;  with  orchard  cultiva- 
tor, 381. 


Index 


501 


Time  as  a  unit  for  division  of  water, 

24'?,. 
Transpiration,    greatest    during    sun- 

stiine,    45,   46 ;    need    of  water,   50 ; 

mechanism,  46;  method,  46  ;  control* 

53. 

Tulare  Exp.  Station,  276. 
Tull,  Jethro,  system  of  intertillage,  157. 
Turbine  wheel,  308. 
Underdraining,  practical  details,  467 ; 

cost,  489;  peat  lands,  491. 

Underflow,  intercepting,  459. 
Underground  water,  diverting  for  irri- 
gation, 304. 
Units  of  water  measurement,  239. 

Vegetables,  garden  irrigation,  385. 
Ventilation  of  soil,  419.     See  soil  venti- 
lation. 
Vir  weir,  78. 
Vosges,  water-meadows,  219. 

Warping,  94,  261. 

Washing  of  soil,  principles  governing, 
337. 

Washington,  dry  farming,  100;  rainfall, 
101,  204. 

Water,  apparent  greater  service  in  arid 
climates,  5,  104;  need  for  nitrifica- 
tion, 12;  fertilizing  value,  14,  93,  251- 
259;  only  one  of  the  necessary  plant" 
foods,  15;  amount  used  by  crops,  16 
21,  24, 30, 36,  37,  38,  39,  41,  46,  60,  97, 122, 
160, 174, 177, 215;  variations  in  amount 
used  by  crops,  39;  used  in  transpira- 
tion, 50;  action  in  plant  feeding,  58; 
amount  needed  for  given  crop,  87; 
least  amount  for  paying  crop,  95;  least 
amount  in  soil  which  permits  growth, 
111,  225;  retained  by  sand,  114,  224; 
insufficiency  for  irrigation,  117;  in 
subsoiled  ground,  136;  lost  through 
mulches,  142,  201 ;  lost  from  wet  soil, 
148;  in  fallow  ground,  155,  225;  capil- 
lary spreading,  161, 330, 377;  conserved 


by  tillage,  164,  353 ;  importance  of 
amount  and  distribution  in  potato 
culture,  172;  duty,  196  (see  Duty  of 
water) ;  amount  for  single  irrigation, 
222,  223, 225, 227, 234 ;  capacity  of  soils, 
224,  353;  best  amount  for  crops,  227; 
measurement,  239;  cold,  for  irriga- 
tion, 249;  value  of  turbid,  for  irriga- 
tion, 259;  alkali  waters,  267,  268,  284, 
285, 287;  supplying,  for  irrigation,  290; 
methods  of  applying,  329 ;  loss  by  per- 
colation, 330;  rate  of  application,  331, 
332,  337;  depth  in  flooding,  346; 
amount  needed  for  lawns  and  parks, 
392  ;  amount  needed  for  sub-irriga- 
tion, 397,  401. 

Water  level,  4^6. 

Water-logged  soil,  11,  334. 

Water-meadows,  16,  92,  219,  251,  359  ; 
English,  76,  360;  use  of  sewage,  220, 
254,  403,  409;  frequency  of  irrigation, 
237;  Belgian,  362;  Italian,  362;  moun- 
tain, 74,  365. 

Water  supply,  for  irrigation  wells,  78, 
84,  85,  86,  251,  393  ;  from  rivers,  290; 
underground  waters,  304;  lifting  by 
water-power,  306  ;  storm  water,  311 ; 
by  wind  power,  312;  by  engines,  324, 
326;  cost,  324;  by  animal  power,  325, 
328;  for  cranberries,  367. 

Water  wheels,  75,  306,  308. 

Weiss,  number  of  breathing  pores,  51. 

Wells,  for  irrigation,  78,  84,  251,  393;  in 
Algeria,  85;  in  Hawaii,  86;  for  lawns 
and  gardens,  393. 

Wheat,  ratio  of  grain  to  straw,  96; 
water  used,  97,  101,  215;  intertillage, 
158;  frequency  of  irrigation,  235. 

Willcocks,  W.,  Egyptian  irrigation,  84, 

:    211;  cost  of  pumping,  326. 

Wilson,  H.  M.,  area  of  land  irrigated, 
88;  duty  of  water,  211;  lifting  water, 
309,  311,  325,  327. 

Winds,  lessening  destructive  effects, 
168. 

Windbreaks,  169. 


502 


Index 


Windmills,  conditions  for  highest  ser- 
vice, 318;  for  lifting  water,  312,  316, 
318,  367;  capacity  for  irrigation,  318; 
use  in  drainage,  463. 


Wind  power,  for  irrigation,  312;  work 
done  by  months,  315;  work  done  by 
10-day  periods,  316. 

Wolff,  A.  R.,  318. 


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LESSONS  WITH  PLANTS 

Suggestions  for  Seeing  and  Interpreting  Some  of  the 
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By   L.  H.  BAILEY 

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There  are  two  ways  of  looking  at  nature.  The  old 
way,  which  you  have  found  so  unsatisfactory,  was  to 
classify  everything  —  to  consider  leaves,  roots,  and  whole 
plants  as  formal  herbarium  specimens,  forgetting  that 
each  had  its  own  story  of  growth  and  development, 
struggle  and  success,  to  tell.  Nothing  stifles  a  natural 
love  for  plants  more  effectually  than  that  old  way. 

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CYCLOPEDIA  OF  AMERICAN 
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Edited  by  L.  H.  BAILEY 

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THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


JUL  2  3 


RL 
MAR 


JUL    91987 
mm  JUN  241987 


30m-l,'15 


U.C.  BERKELEY  LIBRARIES 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


